drm/i915: Register a shrinker to free inactive lists under memory pressure

[safe/jmp/linux-2.6] / drivers / gpu / drm / i915 / i915_gem.c

/*
 * Copyright © 2008 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <eric@anholt.net>
 *
 */

#include "drmP.h"
#include "drm.h"
#include "i915_drm.h"
#include "i915_drv.h"
#include "intel_drv.h"
#include <linux/swap.h>
#include <linux/pci.h>

#define I915_GEM_GPU_DOMAINS    (~(I915_GEM_DOMAIN_CPU | I915_GEM_DOMAIN_GTT))

static void i915_gem_object_flush_gpu_write_domain(struct drm_gem_object *obj);
static void i915_gem_object_flush_gtt_write_domain(struct drm_gem_object *obj);
static void i915_gem_object_flush_cpu_write_domain(struct drm_gem_object *obj);
static int i915_gem_object_set_to_cpu_domain(struct drm_gem_object *obj,
                                             int write);
static int i915_gem_object_set_cpu_read_domain_range(struct drm_gem_object *obj,
                                                     uint64_t offset,
                                                     uint64_t size);
static void i915_gem_object_set_to_full_cpu_read_domain(struct drm_gem_object *obj);
static int i915_gem_object_wait_rendering(struct drm_gem_object *obj);
static int i915_gem_object_bind_to_gtt(struct drm_gem_object *obj,
                                           unsigned alignment);
static void i915_gem_clear_fence_reg(struct drm_gem_object *obj);
static int i915_gem_evict_something(struct drm_device *dev);
static int i915_gem_phys_pwrite(struct drm_device *dev, struct drm_gem_object *obj,
                                struct drm_i915_gem_pwrite *args,
                                struct drm_file *file_priv);

static LIST_HEAD(shrink_list);
static DEFINE_SPINLOCK(shrink_list_lock);

int i915_gem_do_init(struct drm_device *dev, unsigned long start,
                     unsigned long end)
{
        drm_i915_private_t *dev_priv = dev->dev_private;

        if (start >= end ||
            (start & (PAGE_SIZE - 1)) != 0 ||
            (end & (PAGE_SIZE - 1)) != 0) {
                return -EINVAL;
        }

        drm_mm_init(&dev_priv->mm.gtt_space, start,
                    end - start);

        dev->gtt_total = (uint32_t) (end - start);

        return 0;
}

int
i915_gem_init_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file_priv)
{
        struct drm_i915_gem_init *args = data;
        int ret;

        mutex_lock(&dev->struct_mutex);
        ret = i915_gem_do_init(dev, args->gtt_start, args->gtt_end);
        mutex_unlock(&dev->struct_mutex);

        return ret;
}

int
i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
                            struct drm_file *file_priv)
{
        struct drm_i915_gem_get_aperture *args = data;

        if (!(dev->driver->driver_features & DRIVER_GEM))
                return -ENODEV;

        args->aper_size = dev->gtt_total;
        args->aper_available_size = (args->aper_size -
                                     atomic_read(&dev->pin_memory));

        return 0;
}


/**
 * Creates a new mm object and returns a handle to it.
 */
int
i915_gem_create_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file_priv)
{
        struct drm_i915_gem_create *args = data;
        struct drm_gem_object *obj;
        int ret;
        u32 handle;

        args->size = roundup(args->size, PAGE_SIZE);

        /* Allocate the new object */
        obj = drm_gem_object_alloc(dev, args->size);
        if (obj == NULL)
                return -ENOMEM;

        ret = drm_gem_handle_create(file_priv, obj, &handle);
        mutex_lock(&dev->struct_mutex);
        drm_gem_object_handle_unreference(obj);
        mutex_unlock(&dev->struct_mutex);

        if (ret)
                return ret;

        args->handle = handle;

        return 0;
}

static inline int
fast_shmem_read(struct page **pages,
                loff_t page_base, int page_offset,
                char __user *data,
                int length)
{
        char __iomem *vaddr;
        int unwritten;

        vaddr = kmap_atomic(pages[page_base >> PAGE_SHIFT], KM_USER0);
        if (vaddr == NULL)
                return -ENOMEM;
        unwritten = __copy_to_user_inatomic(data, vaddr + page_offset, length);
        kunmap_atomic(vaddr, KM_USER0);

        if (unwritten)
                return -EFAULT;

        return 0;
}

static int i915_gem_object_needs_bit17_swizzle(struct drm_gem_object *obj)
{
        drm_i915_private_t *dev_priv = obj->dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;

        return dev_priv->mm.bit_6_swizzle_x == I915_BIT_6_SWIZZLE_9_10_17 &&
                obj_priv->tiling_mode != I915_TILING_NONE;
}

static inline int
slow_shmem_copy(struct page *dst_page,
                int dst_offset,
                struct page *src_page,
                int src_offset,
                int length)
{
        char *dst_vaddr, *src_vaddr;

        dst_vaddr = kmap_atomic(dst_page, KM_USER0);
        if (dst_vaddr == NULL)
                return -ENOMEM;

        src_vaddr = kmap_atomic(src_page, KM_USER1);
        if (src_vaddr == NULL) {
                kunmap_atomic(dst_vaddr, KM_USER0);
                return -ENOMEM;
        }

        memcpy(dst_vaddr + dst_offset, src_vaddr + src_offset, length);

        kunmap_atomic(src_vaddr, KM_USER1);
        kunmap_atomic(dst_vaddr, KM_USER0);

        return 0;
}

static inline int
slow_shmem_bit17_copy(struct page *gpu_page,
                      int gpu_offset,
                      struct page *cpu_page,
                      int cpu_offset,
                      int length,
                      int is_read)
{
        char *gpu_vaddr, *cpu_vaddr;

        /* Use the unswizzled path if this page isn't affected. */
        if ((page_to_phys(gpu_page) & (1 << 17)) == 0) {
                if (is_read)
                        return slow_shmem_copy(cpu_page, cpu_offset,
                                               gpu_page, gpu_offset, length);
                else
                        return slow_shmem_copy(gpu_page, gpu_offset,
                                               cpu_page, cpu_offset, length);
        }

        gpu_vaddr = kmap_atomic(gpu_page, KM_USER0);
        if (gpu_vaddr == NULL)
                return -ENOMEM;

        cpu_vaddr = kmap_atomic(cpu_page, KM_USER1);
        if (cpu_vaddr == NULL) {
                kunmap_atomic(gpu_vaddr, KM_USER0);
                return -ENOMEM;
        }

        /* Copy the data, XORing A6 with A17 (1). The user already knows he's
         * XORing with the other bits (A9 for Y, A9 and A10 for X)
         */
        while (length > 0) {
                int cacheline_end = ALIGN(gpu_offset + 1, 64);
                int this_length = min(cacheline_end - gpu_offset, length);
                int swizzled_gpu_offset = gpu_offset ^ 64;

                if (is_read) {
                        memcpy(cpu_vaddr + cpu_offset,
                               gpu_vaddr + swizzled_gpu_offset,
                               this_length);
                } else {
                        memcpy(gpu_vaddr + swizzled_gpu_offset,
                               cpu_vaddr + cpu_offset,
                               this_length);
                }
                cpu_offset += this_length;
                gpu_offset += this_length;
                length -= this_length;
        }

        kunmap_atomic(cpu_vaddr, KM_USER1);
        kunmap_atomic(gpu_vaddr, KM_USER0);

        return 0;
}

/**
 * This is the fast shmem pread path, which attempts to copy_from_user directly
 * from the backing pages of the object to the user's address space.  On a
 * fault, it fails so we can fall back to i915_gem_shmem_pwrite_slow().
 */
static int
i915_gem_shmem_pread_fast(struct drm_device *dev, struct drm_gem_object *obj,
                          struct drm_i915_gem_pread *args,
                          struct drm_file *file_priv)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        ssize_t remain;
        loff_t offset, page_base;
        char __user *user_data;
        int page_offset, page_length;
        int ret;

        user_data = (char __user *) (uintptr_t) args->data_ptr;
        remain = args->size;

        mutex_lock(&dev->struct_mutex);

        ret = i915_gem_object_get_pages(obj);
        if (ret != 0)
                goto fail_unlock;

        ret = i915_gem_object_set_cpu_read_domain_range(obj, args->offset,
                                                        args->size);
        if (ret != 0)
                goto fail_put_pages;

        obj_priv = obj->driver_private;
        offset = args->offset;

        while (remain > 0) {
                /* Operation in this page
                 *
                 * page_base = page offset within aperture
                 * page_offset = offset within page
                 * page_length = bytes to copy for this page
                 */
                page_base = (offset & ~(PAGE_SIZE-1));
                page_offset = offset & (PAGE_SIZE-1);
                page_length = remain;
                if ((page_offset + remain) > PAGE_SIZE)
                        page_length = PAGE_SIZE - page_offset;

                ret = fast_shmem_read(obj_priv->pages,
                                      page_base, page_offset,
                                      user_data, page_length);
                if (ret)
                        goto fail_put_pages;

                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

fail_put_pages:
        i915_gem_object_put_pages(obj);
fail_unlock:
        mutex_unlock(&dev->struct_mutex);

        return ret;
}

/**
 * This is the fallback shmem pread path, which allocates temporary storage
 * in kernel space to copy_to_user into outside of the struct_mutex, so we
 * can copy out of the object's backing pages while holding the struct mutex
 * and not take page faults.
 */
static int
i915_gem_shmem_pread_slow(struct drm_device *dev, struct drm_gem_object *obj,
                          struct drm_i915_gem_pread *args,
                          struct drm_file *file_priv)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        struct mm_struct *mm = current->mm;
        struct page **user_pages;
        ssize_t remain;
        loff_t offset, pinned_pages, i;
        loff_t first_data_page, last_data_page, num_pages;
        int shmem_page_index, shmem_page_offset;
        int data_page_index,  data_page_offset;
        int page_length;
        int ret;
        uint64_t data_ptr = args->data_ptr;
        int do_bit17_swizzling;

        remain = args->size;

        /* Pin the user pages containing the data.  We can't fault while
         * holding the struct mutex, yet we want to hold it while
         * dereferencing the user data.
         */
        first_data_page = data_ptr / PAGE_SIZE;
        last_data_page = (data_ptr + args->size - 1) / PAGE_SIZE;
        num_pages = last_data_page - first_data_page + 1;

        user_pages = drm_calloc_large(num_pages, sizeof(struct page *));
        if (user_pages == NULL)
                return -ENOMEM;

        down_read(&mm->mmap_sem);
        pinned_pages = get_user_pages(current, mm, (uintptr_t)args->data_ptr,
                                      num_pages, 1, 0, user_pages, NULL);
        up_read(&mm->mmap_sem);
        if (pinned_pages < num_pages) {
                ret = -EFAULT;
                goto fail_put_user_pages;
        }

        do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);

        mutex_lock(&dev->struct_mutex);

        ret = i915_gem_object_get_pages(obj);
        if (ret != 0)
                goto fail_unlock;

        ret = i915_gem_object_set_cpu_read_domain_range(obj, args->offset,
                                                        args->size);
        if (ret != 0)
                goto fail_put_pages;

        obj_priv = obj->driver_private;
        offset = args->offset;

        while (remain > 0) {
                /* Operation in this page
                 *
                 * shmem_page_index = page number within shmem file
                 * shmem_page_offset = offset within page in shmem file
                 * data_page_index = page number in get_user_pages return
                 * data_page_offset = offset with data_page_index page.
                 * page_length = bytes to copy for this page
                 */
                shmem_page_index = offset / PAGE_SIZE;
                shmem_page_offset = offset & ~PAGE_MASK;
                data_page_index = data_ptr / PAGE_SIZE - first_data_page;
                data_page_offset = data_ptr & ~PAGE_MASK;

                page_length = remain;
                if ((shmem_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - shmem_page_offset;
                if ((data_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - data_page_offset;

                if (do_bit17_swizzling) {
                        ret = slow_shmem_bit17_copy(obj_priv->pages[shmem_page_index],
                                                    shmem_page_offset,
                                                    user_pages[data_page_index],
                                                    data_page_offset,
                                                    page_length,
                                                    1);
                } else {
                        ret = slow_shmem_copy(user_pages[data_page_index],
                                              data_page_offset,
                                              obj_priv->pages[shmem_page_index],
                                              shmem_page_offset,
                                              page_length);
                }
                if (ret)
                        goto fail_put_pages;

                remain -= page_length;
                data_ptr += page_length;
                offset += page_length;
        }

fail_put_pages:
        i915_gem_object_put_pages(obj);
fail_unlock:
        mutex_unlock(&dev->struct_mutex);
fail_put_user_pages:
        for (i = 0; i < pinned_pages; i++) {
                SetPageDirty(user_pages[i]);
                page_cache_release(user_pages[i]);
        }
        drm_free_large(user_pages);

        return ret;
}

/**
 * Reads data from the object referenced by handle.
 *
 * On error, the contents of *data are undefined.
 */
int
i915_gem_pread_ioctl(struct drm_device *dev, void *data,
                     struct drm_file *file_priv)
{
        struct drm_i915_gem_pread *args = data;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;
        int ret;

        obj = drm_gem_object_lookup(dev, file_priv, args->handle);
        if (obj == NULL)
                return -EBADF;
        obj_priv = obj->driver_private;

        /* Bounds check source.
         *
         * XXX: This could use review for overflow issues...
         */
        if (args->offset > obj->size || args->size > obj->size ||
            args->offset + args->size > obj->size) {
                drm_gem_object_unreference(obj);
                return -EINVAL;
        }

        if (i915_gem_object_needs_bit17_swizzle(obj)) {
                ret = i915_gem_shmem_pread_slow(dev, obj, args, file_priv);
        } else {
                ret = i915_gem_shmem_pread_fast(dev, obj, args, file_priv);
                if (ret != 0)
                        ret = i915_gem_shmem_pread_slow(dev, obj, args,
                                                        file_priv);
        }

        drm_gem_object_unreference(obj);

        return ret;
}

/* This is the fast write path which cannot handle
 * page faults in the source data
 */

static inline int
fast_user_write(struct io_mapping *mapping,
                loff_t page_base, int page_offset,
                char __user *user_data,
                int length)
{
        char *vaddr_atomic;
        unsigned long unwritten;

        vaddr_atomic = io_mapping_map_atomic_wc(mapping, page_base);
        unwritten = __copy_from_user_inatomic_nocache(vaddr_atomic + page_offset,
                                                      user_data, length);
        io_mapping_unmap_atomic(vaddr_atomic);
        if (unwritten)
                return -EFAULT;
        return 0;
}

/* Here's the write path which can sleep for
 * page faults
 */

static inline int
slow_kernel_write(struct io_mapping *mapping,
                  loff_t gtt_base, int gtt_offset,
                  struct page *user_page, int user_offset,
                  int length)
{
        char *src_vaddr, *dst_vaddr;
        unsigned long unwritten;

        dst_vaddr = io_mapping_map_atomic_wc(mapping, gtt_base);
        src_vaddr = kmap_atomic(user_page, KM_USER1);
        unwritten = __copy_from_user_inatomic_nocache(dst_vaddr + gtt_offset,
                                                      src_vaddr + user_offset,
                                                      length);
        kunmap_atomic(src_vaddr, KM_USER1);
        io_mapping_unmap_atomic(dst_vaddr);
        if (unwritten)
                return -EFAULT;
        return 0;
}

static inline int
fast_shmem_write(struct page **pages,
                 loff_t page_base, int page_offset,
                 char __user *data,
                 int length)
{
        char __iomem *vaddr;
        unsigned long unwritten;

        vaddr = kmap_atomic(pages[page_base >> PAGE_SHIFT], KM_USER0);
        if (vaddr == NULL)
                return -ENOMEM;
        unwritten = __copy_from_user_inatomic(vaddr + page_offset, data, length);
        kunmap_atomic(vaddr, KM_USER0);

        if (unwritten)
                return -EFAULT;
        return 0;
}

/**
 * This is the fast pwrite path, where we copy the data directly from the
 * user into the GTT, uncached.
 */
static int
i915_gem_gtt_pwrite_fast(struct drm_device *dev, struct drm_gem_object *obj,
                         struct drm_i915_gem_pwrite *args,
                         struct drm_file *file_priv)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        drm_i915_private_t *dev_priv = dev->dev_private;
        ssize_t remain;
        loff_t offset, page_base;
        char __user *user_data;
        int page_offset, page_length;
        int ret;

        user_data = (char __user *) (uintptr_t) args->data_ptr;
        remain = args->size;
        if (!access_ok(VERIFY_READ, user_data, remain))
                return -EFAULT;


        mutex_lock(&dev->struct_mutex);
        ret = i915_gem_object_pin(obj, 0);
        if (ret) {
                mutex_unlock(&dev->struct_mutex);
                return ret;
        }
        ret = i915_gem_object_set_to_gtt_domain(obj, 1);
        if (ret)
                goto fail;

        obj_priv = obj->driver_private;
        offset = obj_priv->gtt_offset + args->offset;

        while (remain > 0) {
                /* Operation in this page
                 *
                 * page_base = page offset within aperture
                 * page_offset = offset within page
                 * page_length = bytes to copy for this page
                 */
                page_base = (offset & ~(PAGE_SIZE-1));
                page_offset = offset & (PAGE_SIZE-1);
                page_length = remain;
                if ((page_offset + remain) > PAGE_SIZE)
                        page_length = PAGE_SIZE - page_offset;

                ret = fast_user_write (dev_priv->mm.gtt_mapping, page_base,
                                       page_offset, user_data, page_length);

                /* If we get a fault while copying data, then (presumably) our
                 * source page isn't available.  Return the error and we'll
                 * retry in the slow path.
                 */
                if (ret)
                        goto fail;

                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

fail:
        i915_gem_object_unpin(obj);
        mutex_unlock(&dev->struct_mutex);

        return ret;
}

/**
 * This is the fallback GTT pwrite path, which uses get_user_pages to pin
 * the memory and maps it using kmap_atomic for copying.
 *
 * This code resulted in x11perf -rgb10text consuming about 10% more CPU
 * than using i915_gem_gtt_pwrite_fast on a G45 (32-bit).
 */
static int
i915_gem_gtt_pwrite_slow(struct drm_device *dev, struct drm_gem_object *obj,
                         struct drm_i915_gem_pwrite *args,
                         struct drm_file *file_priv)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        drm_i915_private_t *dev_priv = dev->dev_private;
        ssize_t remain;
        loff_t gtt_page_base, offset;
        loff_t first_data_page, last_data_page, num_pages;
        loff_t pinned_pages, i;
        struct page **user_pages;
        struct mm_struct *mm = current->mm;
        int gtt_page_offset, data_page_offset, data_page_index, page_length;
        int ret;
        uint64_t data_ptr = args->data_ptr;

        remain = args->size;

        /* Pin the user pages containing the data.  We can't fault while
         * holding the struct mutex, and all of the pwrite implementations
         * want to hold it while dereferencing the user data.
         */
        first_data_page = data_ptr / PAGE_SIZE;
        last_data_page = (data_ptr + args->size - 1) / PAGE_SIZE;
        num_pages = last_data_page - first_data_page + 1;

        user_pages = drm_calloc_large(num_pages, sizeof(struct page *));
        if (user_pages == NULL)
                return -ENOMEM;

        down_read(&mm->mmap_sem);
        pinned_pages = get_user_pages(current, mm, (uintptr_t)args->data_ptr,
                                      num_pages, 0, 0, user_pages, NULL);
        up_read(&mm->mmap_sem);
        if (pinned_pages < num_pages) {
                ret = -EFAULT;
                goto out_unpin_pages;
        }

        mutex_lock(&dev->struct_mutex);
        ret = i915_gem_object_pin(obj, 0);
        if (ret)
                goto out_unlock;

        ret = i915_gem_object_set_to_gtt_domain(obj, 1);
        if (ret)
                goto out_unpin_object;

        obj_priv = obj->driver_private;
        offset = obj_priv->gtt_offset + args->offset;

        while (remain > 0) {
                /* Operation in this page
                 *
                 * gtt_page_base = page offset within aperture
                 * gtt_page_offset = offset within page in aperture
                 * data_page_index = page number in get_user_pages return
                 * data_page_offset = offset with data_page_index page.
                 * page_length = bytes to copy for this page
                 */
                gtt_page_base = offset & PAGE_MASK;
                gtt_page_offset = offset & ~PAGE_MASK;
                data_page_index = data_ptr / PAGE_SIZE - first_data_page;
                data_page_offset = data_ptr & ~PAGE_MASK;

                page_length = remain;
                if ((gtt_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - gtt_page_offset;
                if ((data_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - data_page_offset;

                ret = slow_kernel_write(dev_priv->mm.gtt_mapping,
                                        gtt_page_base, gtt_page_offset,
                                        user_pages[data_page_index],
                                        data_page_offset,
                                        page_length);

                /* If we get a fault while copying data, then (presumably) our
                 * source page isn't available.  Return the error and we'll
                 * retry in the slow path.
                 */
                if (ret)
                        goto out_unpin_object;

                remain -= page_length;
                offset += page_length;
                data_ptr += page_length;
        }

out_unpin_object:
        i915_gem_object_unpin(obj);
out_unlock:
        mutex_unlock(&dev->struct_mutex);
out_unpin_pages:
        for (i = 0; i < pinned_pages; i++)
                page_cache_release(user_pages[i]);
        drm_free_large(user_pages);

        return ret;
}

/**
 * This is the fast shmem pwrite path, which attempts to directly
 * copy_from_user into the kmapped pages backing the object.
 */
static int
i915_gem_shmem_pwrite_fast(struct drm_device *dev, struct drm_gem_object *obj,
                           struct drm_i915_gem_pwrite *args,
                           struct drm_file *file_priv)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        ssize_t remain;
        loff_t offset, page_base;
        char __user *user_data;
        int page_offset, page_length;
        int ret;

        user_data = (char __user *) (uintptr_t) args->data_ptr;
        remain = args->size;

        mutex_lock(&dev->struct_mutex);

        ret = i915_gem_object_get_pages(obj);
        if (ret != 0)
                goto fail_unlock;

        ret = i915_gem_object_set_to_cpu_domain(obj, 1);
        if (ret != 0)
                goto fail_put_pages;

        obj_priv = obj->driver_private;
        offset = args->offset;
        obj_priv->dirty = 1;

        while (remain > 0) {
                /* Operation in this page
                 *
                 * page_base = page offset within aperture
                 * page_offset = offset within page
                 * page_length = bytes to copy for this page
                 */
                page_base = (offset & ~(PAGE_SIZE-1));
                page_offset = offset & (PAGE_SIZE-1);
                page_length = remain;
                if ((page_offset + remain) > PAGE_SIZE)
                        page_length = PAGE_SIZE - page_offset;

                ret = fast_shmem_write(obj_priv->pages,
                                       page_base, page_offset,
                                       user_data, page_length);
                if (ret)
                        goto fail_put_pages;

                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

fail_put_pages:
        i915_gem_object_put_pages(obj);
fail_unlock:
        mutex_unlock(&dev->struct_mutex);

        return ret;
}

/**
 * This is the fallback shmem pwrite path, which uses get_user_pages to pin
 * the memory and maps it using kmap_atomic for copying.
 *
 * This avoids taking mmap_sem for faulting on the user's address while the
 * struct_mutex is held.
 */
static int
i915_gem_shmem_pwrite_slow(struct drm_device *dev, struct drm_gem_object *obj,
                           struct drm_i915_gem_pwrite *args,
                           struct drm_file *file_priv)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        struct mm_struct *mm = current->mm;
        struct page **user_pages;
        ssize_t remain;
        loff_t offset, pinned_pages, i;
        loff_t first_data_page, last_data_page, num_pages;
        int shmem_page_index, shmem_page_offset;
        int data_page_index,  data_page_offset;
        int page_length;
        int ret;
        uint64_t data_ptr = args->data_ptr;
        int do_bit17_swizzling;

        remain = args->size;

        /* Pin the user pages containing the data.  We can't fault while
         * holding the struct mutex, and all of the pwrite implementations
         * want to hold it while dereferencing the user data.
         */
        first_data_page = data_ptr / PAGE_SIZE;
        last_data_page = (data_ptr + args->size - 1) / PAGE_SIZE;
        num_pages = last_data_page - first_data_page + 1;

        user_pages = drm_calloc_large(num_pages, sizeof(struct page *));
        if (user_pages == NULL)
                return -ENOMEM;

        down_read(&mm->mmap_sem);
        pinned_pages = get_user_pages(current, mm, (uintptr_t)args->data_ptr,
                                      num_pages, 0, 0, user_pages, NULL);
        up_read(&mm->mmap_sem);
        if (pinned_pages < num_pages) {
                ret = -EFAULT;
                goto fail_put_user_pages;
        }

        do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);

        mutex_lock(&dev->struct_mutex);

        ret = i915_gem_object_get_pages(obj);
        if (ret != 0)
                goto fail_unlock;

        ret = i915_gem_object_set_to_cpu_domain(obj, 1);
        if (ret != 0)
                goto fail_put_pages;

        obj_priv = obj->driver_private;
        offset = args->offset;
        obj_priv->dirty = 1;

        while (remain > 0) {
                /* Operation in this page
                 *
                 * shmem_page_index = page number within shmem file
                 * shmem_page_offset = offset within page in shmem file
                 * data_page_index = page number in get_user_pages return
                 * data_page_offset = offset with data_page_index page.
                 * page_length = bytes to copy for this page
                 */
                shmem_page_index = offset / PAGE_SIZE;
                shmem_page_offset = offset & ~PAGE_MASK;
                data_page_index = data_ptr / PAGE_SIZE - first_data_page;
                data_page_offset = data_ptr & ~PAGE_MASK;

                page_length = remain;
                if ((shmem_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - shmem_page_offset;
                if ((data_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - data_page_offset;

                if (do_bit17_swizzling) {
                        ret = slow_shmem_bit17_copy(obj_priv->pages[shmem_page_index],
                                                    shmem_page_offset,
                                                    user_pages[data_page_index],
                                                    data_page_offset,
                                                    page_length,
                                                    0);
                } else {
                        ret = slow_shmem_copy(obj_priv->pages[shmem_page_index],
                                              shmem_page_offset,
                                              user_pages[data_page_index],
                                              data_page_offset,
                                              page_length);
                }
                if (ret)
                        goto fail_put_pages;

                remain -= page_length;
                data_ptr += page_length;
                offset += page_length;
        }

fail_put_pages:
        i915_gem_object_put_pages(obj);
fail_unlock:
        mutex_unlock(&dev->struct_mutex);
fail_put_user_pages:
        for (i = 0; i < pinned_pages; i++)
                page_cache_release(user_pages[i]);
        drm_free_large(user_pages);

        return ret;
}

/**
 * Writes data to the object referenced by handle.
 *
 * On error, the contents of the buffer that were to be modified are undefined.
 */
int
i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file_priv)
{
        struct drm_i915_gem_pwrite *args = data;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;
        int ret = 0;

        obj = drm_gem_object_lookup(dev, file_priv, args->handle);
        if (obj == NULL)
                return -EBADF;
        obj_priv = obj->driver_private;

        /* Bounds check destination.
         *
         * XXX: This could use review for overflow issues...
         */
        if (args->offset > obj->size || args->size > obj->size ||
            args->offset + args->size > obj->size) {
                drm_gem_object_unreference(obj);
                return -EINVAL;
        }

        /* We can only do the GTT pwrite on untiled buffers, as otherwise
         * it would end up going through the fenced access, and we'll get
         * different detiling behavior between reading and writing.
         * pread/pwrite currently are reading and writing from the CPU
         * perspective, requiring manual detiling by the client.
         */
        if (obj_priv->phys_obj)
                ret = i915_gem_phys_pwrite(dev, obj, args, file_priv);
        else if (obj_priv->tiling_mode == I915_TILING_NONE &&
                 dev->gtt_total != 0) {
                ret = i915_gem_gtt_pwrite_fast(dev, obj, args, file_priv);
                if (ret == -EFAULT) {
                        ret = i915_gem_gtt_pwrite_slow(dev, obj, args,
                                                       file_priv);
                }
        } else if (i915_gem_object_needs_bit17_swizzle(obj)) {
                ret = i915_gem_shmem_pwrite_slow(dev, obj, args, file_priv);
        } else {
                ret = i915_gem_shmem_pwrite_fast(dev, obj, args, file_priv);
                if (ret == -EFAULT) {
                        ret = i915_gem_shmem_pwrite_slow(dev, obj, args,
                                                         file_priv);
                }
        }

#if WATCH_PWRITE
        if (ret)
                DRM_INFO("pwrite failed %d\n", ret);
#endif

        drm_gem_object_unreference(obj);

        return ret;
}

/**
 * Called when user space prepares to use an object with the CPU, either
 * through the mmap ioctl's mapping or a GTT mapping.
 */
int
i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file_priv)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_set_domain *args = data;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;
        uint32_t read_domains = args->read_domains;
        uint32_t write_domain = args->write_domain;
        int ret;

        if (!(dev->driver->driver_features & DRIVER_GEM))
                return -ENODEV;

        /* Only handle setting domains to types used by the CPU. */
        if (write_domain & I915_GEM_GPU_DOMAINS)
                return -EINVAL;

        if (read_domains & I915_GEM_GPU_DOMAINS)
                return -EINVAL;

        /* Having something in the write domain implies it's in the read
         * domain, and only that read domain.  Enforce that in the request.
         */
        if (write_domain != 0 && read_domains != write_domain)
                return -EINVAL;

        obj = drm_gem_object_lookup(dev, file_priv, args->handle);
        if (obj == NULL)
                return -EBADF;
        obj_priv = obj->driver_private;

        mutex_lock(&dev->struct_mutex);

        intel_mark_busy(dev, obj);

#if WATCH_BUF
        DRM_INFO("set_domain_ioctl %p(%zd), %08x %08x\n",
                 obj, obj->size, read_domains, write_domain);
#endif
        if (read_domains & I915_GEM_DOMAIN_GTT) {
                ret = i915_gem_object_set_to_gtt_domain(obj, write_domain != 0);

                /* Update the LRU on the fence for the CPU access that's
                 * about to occur.
                 */
                if (obj_priv->fence_reg != I915_FENCE_REG_NONE) {
                        list_move_tail(&obj_priv->fence_list,
                                       &dev_priv->mm.fence_list);
                }

                /* Silently promote "you're not bound, there was nothing to do"
                 * to success, since the client was just asking us to
                 * make sure everything was done.
                 */
                if (ret == -EINVAL)
                        ret = 0;
        } else {
                ret = i915_gem_object_set_to_cpu_domain(obj, write_domain != 0);
        }

        drm_gem_object_unreference(obj);
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 * Called when user space has done writes to this buffer
 */
int
i915_gem_sw_finish_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file_priv)
{
        struct drm_i915_gem_sw_finish *args = data;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;
        int ret = 0;

        if (!(dev->driver->driver_features & DRIVER_GEM))
                return -ENODEV;

        mutex_lock(&dev->struct_mutex);
        obj = drm_gem_object_lookup(dev, file_priv, args->handle);
        if (obj == NULL) {
                mutex_unlock(&dev->struct_mutex);
                return -EBADF;
        }

#if WATCH_BUF
        DRM_INFO("%s: sw_finish %d (%p %zd)\n",
                 __func__, args->handle, obj, obj->size);
#endif
        obj_priv = obj->driver_private;

        /* Pinned buffers may be scanout, so flush the cache */
        if (obj_priv->pin_count)
                i915_gem_object_flush_cpu_write_domain(obj);

        drm_gem_object_unreference(obj);
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 * Maps the contents of an object, returning the address it is mapped
 * into.
 *
 * While the mapping holds a reference on the contents of the object, it doesn't
 * imply a ref on the object itself.
 */
int
i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
                   struct drm_file *file_priv)
{
        struct drm_i915_gem_mmap *args = data;
        struct drm_gem_object *obj;
        loff_t offset;
        unsigned long addr;

        if (!(dev->driver->driver_features & DRIVER_GEM))
                return -ENODEV;

        obj = drm_gem_object_lookup(dev, file_priv, args->handle);
        if (obj == NULL)
                return -EBADF;

        offset = args->offset;

        down_write(&current->mm->mmap_sem);
        addr = do_mmap(obj->filp, 0, args->size,
                       PROT_READ | PROT_WRITE, MAP_SHARED,
                       args->offset);
        up_write(&current->mm->mmap_sem);
        mutex_lock(&dev->struct_mutex);
        drm_gem_object_unreference(obj);
        mutex_unlock(&dev->struct_mutex);
        if (IS_ERR((void *)addr))
                return addr;

        args->addr_ptr = (uint64_t) addr;

        return 0;
}

/**
 * i915_gem_fault - fault a page into the GTT
 * vma: VMA in question
 * vmf: fault info
 *
 * The fault handler is set up by drm_gem_mmap() when a object is GTT mapped
 * from userspace.  The fault handler takes care of binding the object to
 * the GTT (if needed), allocating and programming a fence register (again,
 * only if needed based on whether the old reg is still valid or the object
 * is tiled) and inserting a new PTE into the faulting process.
 *
 * Note that the faulting process may involve evicting existing objects
 * from the GTT and/or fence registers to make room.  So performance may
 * suffer if the GTT working set is large or there are few fence registers
 * left.
 */
int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct drm_gem_object *obj = vma->vm_private_data;
        struct drm_device *dev = obj->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        pgoff_t page_offset;
        unsigned long pfn;
        int ret = 0;
        bool write = !!(vmf->flags & FAULT_FLAG_WRITE);

        /* We don't use vmf->pgoff since that has the fake offset */
        page_offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >>
                PAGE_SHIFT;

        /* Now bind it into the GTT if needed */
        mutex_lock(&dev->struct_mutex);
        if (!obj_priv->gtt_space) {
                ret = i915_gem_object_bind_to_gtt(obj, 0);
                if (ret) {
                        mutex_unlock(&dev->struct_mutex);
                        return VM_FAULT_SIGBUS;
                }
                list_add_tail(&obj_priv->list, &dev_priv->mm.inactive_list);

                ret = i915_gem_object_set_to_gtt_domain(obj, write);
                if (ret) {
                        mutex_unlock(&dev->struct_mutex);
                        return VM_FAULT_SIGBUS;
                }
        }

        /* Need a new fence register? */
        if (obj_priv->tiling_mode != I915_TILING_NONE) {
                ret = i915_gem_object_get_fence_reg(obj);
                if (ret) {
                        mutex_unlock(&dev->struct_mutex);
                        return VM_FAULT_SIGBUS;
                }
        }

        pfn = ((dev->agp->base + obj_priv->gtt_offset) >> PAGE_SHIFT) +
                page_offset;

        /* Finally, remap it using the new GTT offset */
        ret = vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);

        mutex_unlock(&dev->struct_mutex);

        switch (ret) {
        case -ENOMEM:
        case -EAGAIN:
                return VM_FAULT_OOM;
        case -EFAULT:
        case -EINVAL:
                return VM_FAULT_SIGBUS;
        default:
                return VM_FAULT_NOPAGE;
        }
}

/**
 * i915_gem_create_mmap_offset - create a fake mmap offset for an object
 * @obj: obj in question
 *
 * GEM memory mapping works by handing back to userspace a fake mmap offset
 * it can use in a subsequent mmap(2) call.  The DRM core code then looks
 * up the object based on the offset and sets up the various memory mapping
 * structures.
 *
 * This routine allocates and attaches a fake offset for @obj.
 */
static int
i915_gem_create_mmap_offset(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct drm_gem_mm *mm = dev->mm_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        struct drm_map_list *list;
        struct drm_local_map *map;
        int ret = 0;

        /* Set the object up for mmap'ing */
        list = &obj->map_list;
        list->map = kzalloc(sizeof(struct drm_map_list), GFP_KERNEL);
        if (!list->map)
                return -ENOMEM;

        map = list->map;
        map->type = _DRM_GEM;
        map->size = obj->size;
        map->handle = obj;

        /* Get a DRM GEM mmap offset allocated... */
        list->file_offset_node = drm_mm_search_free(&mm->offset_manager,
                                                    obj->size / PAGE_SIZE, 0, 0);
        if (!list->file_offset_node) {
                DRM_ERROR("failed to allocate offset for bo %d\n", obj->name);
                ret = -ENOMEM;
                goto out_free_list;
        }

        list->file_offset_node = drm_mm_get_block(list->file_offset_node,
                                                  obj->size / PAGE_SIZE, 0);
        if (!list->file_offset_node) {
                ret = -ENOMEM;
                goto out_free_list;
        }

        list->hash.key = list->file_offset_node->start;
        if (drm_ht_insert_item(&mm->offset_hash, &list->hash)) {
                DRM_ERROR("failed to add to map hash\n");
                goto out_free_mm;
        }

        /* By now we should be all set, any drm_mmap request on the offset
         * below will get to our mmap & fault handler */
        obj_priv->mmap_offset = ((uint64_t) list->hash.key) << PAGE_SHIFT;

        return 0;

out_free_mm:
        drm_mm_put_block(list->file_offset_node);
out_free_list:
        kfree(list->map);

        return ret;
}

/**
 * i915_gem_release_mmap - remove physical page mappings
 * @obj: obj in question
 *
 * Preserve the reservation of the mmaping with the DRM core code, but
 * relinquish ownership of the pages back to the system.
 *
 * It is vital that we remove the page mapping if we have mapped a tiled
 * object through the GTT and then lose the fence register due to
 * resource pressure. Similarly if the object has been moved out of the
 * aperture, than pages mapped into userspace must be revoked. Removing the
 * mapping will then trigger a page fault on the next user access, allowing
 * fixup by i915_gem_fault().
 */
void
i915_gem_release_mmap(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;

        if (dev->dev_mapping)
                unmap_mapping_range(dev->dev_mapping,
                                    obj_priv->mmap_offset, obj->size, 1);
}

static void
i915_gem_free_mmap_offset(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        struct drm_gem_mm *mm = dev->mm_private;
        struct drm_map_list *list;

        list = &obj->map_list;
        drm_ht_remove_item(&mm->offset_hash, &list->hash);

        if (list->file_offset_node) {
                drm_mm_put_block(list->file_offset_node);
                list->file_offset_node = NULL;
        }

        if (list->map) {
                kfree(list->map);
                list->map = NULL;
        }

        obj_priv->mmap_offset = 0;
}

/**
 * i915_gem_get_gtt_alignment - return required GTT alignment for an object
 * @obj: object to check
 *
 * Return the required GTT alignment for an object, taking into account
 * potential fence register mapping if needed.
 */
static uint32_t
i915_gem_get_gtt_alignment(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int start, i;

        /*
         * Minimum alignment is 4k (GTT page size), but might be greater
         * if a fence register is needed for the object.
         */
        if (IS_I965G(dev) || obj_priv->tiling_mode == I915_TILING_NONE)
                return 4096;

        /*
         * Previous chips need to be aligned to the size of the smallest
         * fence register that can contain the object.
         */
        if (IS_I9XX(dev))
                start = 1024*1024;
        else
                start = 512*1024;

        for (i = start; i < obj->size; i <<= 1)
                ;

        return i;
}

/**
 * i915_gem_mmap_gtt_ioctl - prepare an object for GTT mmap'ing
 * @dev: DRM device
 * @data: GTT mapping ioctl data
 * @file_priv: GEM object info
 *
 * Simply returns the fake offset to userspace so it can mmap it.
 * The mmap call will end up in drm_gem_mmap(), which will set things
 * up so we can get faults in the handler above.
 *
 * The fault handler will take care of binding the object into the GTT
 * (since it may have been evicted to make room for something), allocating
 * a fence register, and mapping the appropriate aperture address into
 * userspace.
 */
int
i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file_priv)
{
        struct drm_i915_gem_mmap_gtt *args = data;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;
        int ret;

        if (!(dev->driver->driver_features & DRIVER_GEM))
                return -ENODEV;

        obj = drm_gem_object_lookup(dev, file_priv, args->handle);
        if (obj == NULL)
                return -EBADF;

        mutex_lock(&dev->struct_mutex);

        obj_priv = obj->driver_private;

        if (!obj_priv->mmap_offset) {
                ret = i915_gem_create_mmap_offset(obj);
                if (ret) {
                        drm_gem_object_unreference(obj);
                        mutex_unlock(&dev->struct_mutex);
                        return ret;
                }
        }

        args->offset = obj_priv->mmap_offset;

        /*
         * Pull it into the GTT so that we have a page list (makes the
         * initial fault faster and any subsequent flushing possible).
         */
        if (!obj_priv->agp_mem) {
                ret = i915_gem_object_bind_to_gtt(obj, 0);
                if (ret) {
                        drm_gem_object_unreference(obj);
                        mutex_unlock(&dev->struct_mutex);
                        return ret;
                }
                list_add_tail(&obj_priv->list, &dev_priv->mm.inactive_list);
        }

        drm_gem_object_unreference(obj);
        mutex_unlock(&dev->struct_mutex);

        return 0;
}

void
i915_gem_object_put_pages(struct drm_gem_object *obj)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int page_count = obj->size / PAGE_SIZE;
        int i;

        BUG_ON(obj_priv->pages_refcount == 0);

        if (--obj_priv->pages_refcount != 0)
                return;

        if (obj_priv->tiling_mode != I915_TILING_NONE)
                i915_gem_object_save_bit_17_swizzle(obj);

        for (i = 0; i < page_count; i++)
                if (obj_priv->pages[i] != NULL) {
                        if (obj_priv->dirty)
                                set_page_dirty(obj_priv->pages[i]);
                        mark_page_accessed(obj_priv->pages[i]);
                        page_cache_release(obj_priv->pages[i]);
                }
        obj_priv->dirty = 0;

        drm_free_large(obj_priv->pages);
        obj_priv->pages = NULL;
}

static void
i915_gem_object_move_to_active(struct drm_gem_object *obj, uint32_t seqno)
{
        struct drm_device *dev = obj->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;

        /* Add a reference if we're newly entering the active list. */
        if (!obj_priv->active) {
                drm_gem_object_reference(obj);
                obj_priv->active = 1;
        }
        /* Move from whatever list we were on to the tail of execution. */
        spin_lock(&dev_priv->mm.active_list_lock);
        list_move_tail(&obj_priv->list,
                       &dev_priv->mm.active_list);
        spin_unlock(&dev_priv->mm.active_list_lock);
        obj_priv->last_rendering_seqno = seqno;
}

static void
i915_gem_object_move_to_flushing(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;

        BUG_ON(!obj_priv->active);
        list_move_tail(&obj_priv->list, &dev_priv->mm.flushing_list);
        obj_priv->last_rendering_seqno = 0;
}

static void
i915_gem_object_move_to_inactive(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;

        i915_verify_inactive(dev, __FILE__, __LINE__);
        if (obj_priv->pin_count != 0)
                list_del_init(&obj_priv->list);
        else
                list_move_tail(&obj_priv->list, &dev_priv->mm.inactive_list);

        obj_priv->last_rendering_seqno = 0;
        if (obj_priv->active) {
                obj_priv->active = 0;
                drm_gem_object_unreference(obj);
        }
        i915_verify_inactive(dev, __FILE__, __LINE__);
}

/**
 * Creates a new sequence number, emitting a write of it to the status page
 * plus an interrupt, which will trigger i915_user_interrupt_handler.
 *
 * Must be called with struct_lock held.
 *
 * Returned sequence numbers are nonzero on success.
 */
static uint32_t
i915_add_request(struct drm_device *dev, struct drm_file *file_priv,
                 uint32_t flush_domains)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_file_private *i915_file_priv = NULL;
        struct drm_i915_gem_request *request;
        uint32_t seqno;
        int was_empty;
        RING_LOCALS;

        if (file_priv != NULL)
                i915_file_priv = file_priv->driver_priv;

        request = kzalloc(sizeof(*request), GFP_KERNEL);
        if (request == NULL)
                return 0;

        /* Grab the seqno we're going to make this request be, and bump the
         * next (skipping 0 so it can be the reserved no-seqno value).
         */
        seqno = dev_priv->mm.next_gem_seqno;
        dev_priv->mm.next_gem_seqno++;
        if (dev_priv->mm.next_gem_seqno == 0)
                dev_priv->mm.next_gem_seqno++;

        BEGIN_LP_RING(4);
        OUT_RING(MI_STORE_DWORD_INDEX);
        OUT_RING(I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
        OUT_RING(seqno);

        OUT_RING(MI_USER_INTERRUPT);
        ADVANCE_LP_RING();

        DRM_DEBUG("%d\n", seqno);

        request->seqno = seqno;
        request->emitted_jiffies = jiffies;
        was_empty = list_empty(&dev_priv->mm.request_list);
        list_add_tail(&request->list, &dev_priv->mm.request_list);
        if (i915_file_priv) {
                list_add_tail(&request->client_list,
                              &i915_file_priv->mm.request_list);
        } else {
                INIT_LIST_HEAD(&request->client_list);
        }

        /* Associate any objects on the flushing list matching the write
         * domain we're flushing with our flush.
         */
        if (flush_domains != 0) {
                struct drm_i915_gem_object *obj_priv, *next;

                list_for_each_entry_safe(obj_priv, next,
                                         &dev_priv->mm.flushing_list, list) {
                        struct drm_gem_object *obj = obj_priv->obj;

                        if ((obj->write_domain & flush_domains) ==
                            obj->write_domain) {
                                obj->write_domain = 0;
                                i915_gem_object_move_to_active(obj, seqno);
                        }
                }

        }

        if (!dev_priv->mm.suspended) {
                mod_timer(&dev_priv->hangcheck_timer, jiffies + DRM_I915_HANGCHECK_PERIOD);
                if (was_empty)
                        queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, HZ);
        }
        return seqno;
}

/**
 * Command execution barrier
 *
 * Ensures that all commands in the ring are finished
 * before signalling the CPU
 */
static uint32_t
i915_retire_commands(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        uint32_t cmd = MI_FLUSH | MI_NO_WRITE_FLUSH;
        uint32_t flush_domains = 0;
        RING_LOCALS;

        /* The sampler always gets flushed on i965 (sigh) */
        if (IS_I965G(dev))
                flush_domains |= I915_GEM_DOMAIN_SAMPLER;
        BEGIN_LP_RING(2);
        OUT_RING(cmd);
        OUT_RING(0); /* noop */
        ADVANCE_LP_RING();
        return flush_domains;
}

/**
 * Moves buffers associated only with the given active seqno from the active
 * to inactive list, potentially freeing them.
 */
static void
i915_gem_retire_request(struct drm_device *dev,
                        struct drm_i915_gem_request *request)
{
        drm_i915_private_t *dev_priv = dev->dev_private;

        /* Move any buffers on the active list that are no longer referenced
         * by the ringbuffer to the flushing/inactive lists as appropriate.
         */
        spin_lock(&dev_priv->mm.active_list_lock);
        while (!list_empty(&dev_priv->mm.active_list)) {
                struct drm_gem_object *obj;
                struct drm_i915_gem_object *obj_priv;

                obj_priv = list_first_entry(&dev_priv->mm.active_list,
                                            struct drm_i915_gem_object,
                                            list);
                obj = obj_priv->obj;

                /* If the seqno being retired doesn't match the oldest in the
                 * list, then the oldest in the list must still be newer than
                 * this seqno.
                 */
                if (obj_priv->last_rendering_seqno != request->seqno)
                        goto out;

#if WATCH_LRU
                DRM_INFO("%s: retire %d moves to inactive list %p\n",
                         __func__, request->seqno, obj);
#endif

                if (obj->write_domain != 0)
                        i915_gem_object_move_to_flushing(obj);
                else {
                        /* Take a reference on the object so it won't be
                         * freed while the spinlock is held.  The list
                         * protection for this spinlock is safe when breaking
                         * the lock like this since the next thing we do
                         * is just get the head of the list again.
                         */
                        drm_gem_object_reference(obj);
                        i915_gem_object_move_to_inactive(obj);
                        spin_unlock(&dev_priv->mm.active_list_lock);
                        drm_gem_object_unreference(obj);
                        spin_lock(&dev_priv->mm.active_list_lock);
                }
        }
out:
        spin_unlock(&dev_priv->mm.active_list_lock);
}

/**
 * Returns true if seq1 is later than seq2.
 */
bool
i915_seqno_passed(uint32_t seq1, uint32_t seq2)
{
        return (int32_t)(seq1 - seq2) >= 0;
}

uint32_t
i915_get_gem_seqno(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;

        return READ_HWSP(dev_priv, I915_GEM_HWS_INDEX);
}

/**
 * This function clears the request list as sequence numbers are passed.
 */
void
i915_gem_retire_requests(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        uint32_t seqno;

        if (!dev_priv->hw_status_page)
                return;

        seqno = i915_get_gem_seqno(dev);

        while (!list_empty(&dev_priv->mm.request_list)) {
                struct drm_i915_gem_request *request;
                uint32_t retiring_seqno;

                request = list_first_entry(&dev_priv->mm.request_list,
                                           struct drm_i915_gem_request,
                                           list);
                retiring_seqno = request->seqno;

                if (i915_seqno_passed(seqno, retiring_seqno) ||
                    atomic_read(&dev_priv->mm.wedged)) {
                        i915_gem_retire_request(dev, request);

                        list_del(&request->list);
                        list_del(&request->client_list);
                        kfree(request);
                } else
                        break;
        }
}

void
i915_gem_retire_work_handler(struct work_struct *work)
{
        drm_i915_private_t *dev_priv;
        struct drm_device *dev;

        dev_priv = container_of(work, drm_i915_private_t,
                                mm.retire_work.work);
        dev = dev_priv->dev;

        mutex_lock(&dev->struct_mutex);
        i915_gem_retire_requests(dev);
        if (!dev_priv->mm.suspended &&
            !list_empty(&dev_priv->mm.request_list))
                queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, HZ);
        mutex_unlock(&dev->struct_mutex);
}

/**
 * Waits for a sequence number to be signaled, and cleans up the
 * request and object lists appropriately for that event.
 */
static int
i915_wait_request(struct drm_device *dev, uint32_t seqno)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        u32 ier;
        int ret = 0;

        BUG_ON(seqno == 0);

        if (atomic_read(&dev_priv->mm.wedged))
                return -EIO;

        if (!i915_seqno_passed(i915_get_gem_seqno(dev), seqno)) {
                if (IS_IGDNG(dev))
                        ier = I915_READ(DEIER) | I915_READ(GTIER);
                else
                        ier = I915_READ(IER);
                if (!ier) {
                        DRM_ERROR("something (likely vbetool) disabled "
                                  "interrupts, re-enabling\n");
                        i915_driver_irq_preinstall(dev);
                        i915_driver_irq_postinstall(dev);
                }

                dev_priv->mm.waiting_gem_seqno = seqno;
                i915_user_irq_get(dev);
                ret = wait_event_interruptible(dev_priv->irq_queue,
                                               i915_seqno_passed(i915_get_gem_seqno(dev),
                                                                 seqno) ||
                                               atomic_read(&dev_priv->mm.wedged));
                i915_user_irq_put(dev);
                dev_priv->mm.waiting_gem_seqno = 0;
        }
        if (atomic_read(&dev_priv->mm.wedged))
                ret = -EIO;

        if (ret && ret != -ERESTARTSYS)
                DRM_ERROR("%s returns %d (awaiting %d at %d)\n",
                          __func__, ret, seqno, i915_get_gem_seqno(dev));

        /* Directly dispatch request retiring.  While we have the work queue
         * to handle this, the waiter on a request often wants an associated
         * buffer to have made it to the inactive list, and we would need
         * a separate wait queue to handle that.
         */
        if (ret == 0)
                i915_gem_retire_requests(dev);

        return ret;
}

static void
i915_gem_flush(struct drm_device *dev,
               uint32_t invalidate_domains,
               uint32_t flush_domains)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        uint32_t cmd;
        RING_LOCALS;

#if WATCH_EXEC
        DRM_INFO("%s: invalidate %08x flush %08x\n", __func__,
                  invalidate_domains, flush_domains);
#endif

        if (flush_domains & I915_GEM_DOMAIN_CPU)
                drm_agp_chipset_flush(dev);

        if ((invalidate_domains | flush_domains) & I915_GEM_GPU_DOMAINS) {
                /*
                 * read/write caches:
                 *
                 * I915_GEM_DOMAIN_RENDER is always invalidated, but is
                 * only flushed if MI_NO_WRITE_FLUSH is unset.  On 965, it is
                 * also flushed at 2d versus 3d pipeline switches.
                 *
                 * read-only caches:
                 *
                 * I915_GEM_DOMAIN_SAMPLER is flushed on pre-965 if
                 * MI_READ_FLUSH is set, and is always flushed on 965.
                 *
                 * I915_GEM_DOMAIN_COMMAND may not exist?
                 *
                 * I915_GEM_DOMAIN_INSTRUCTION, which exists on 965, is
                 * invalidated when MI_EXE_FLUSH is set.
                 *
                 * I915_GEM_DOMAIN_VERTEX, which exists on 965, is
                 * invalidated with every MI_FLUSH.
                 *
                 * TLBs:
                 *
                 * On 965, TLBs associated with I915_GEM_DOMAIN_COMMAND
                 * and I915_GEM_DOMAIN_CPU in are invalidated at PTE write and
                 * I915_GEM_DOMAIN_RENDER and I915_GEM_DOMAIN_SAMPLER
                 * are flushed at any MI_FLUSH.
                 */

                cmd = MI_FLUSH | MI_NO_WRITE_FLUSH;
                if ((invalidate_domains|flush_domains) &
                    I915_GEM_DOMAIN_RENDER)
                        cmd &= ~MI_NO_WRITE_FLUSH;
                if (!IS_I965G(dev)) {
                        /*
                         * On the 965, the sampler cache always gets flushed
                         * and this bit is reserved.
                         */
                        if (invalidate_domains & I915_GEM_DOMAIN_SAMPLER)
                                cmd |= MI_READ_FLUSH;
                }
                if (invalidate_domains & I915_GEM_DOMAIN_INSTRUCTION)
                        cmd |= MI_EXE_FLUSH;

#if WATCH_EXEC
                DRM_INFO("%s: queue flush %08x to ring\n", __func__, cmd);
#endif
                BEGIN_LP_RING(2);
                OUT_RING(cmd);
                OUT_RING(0); /* noop */
                ADVANCE_LP_RING();
        }
}

/**
 * Ensures that all rendering to the object has completed and the object is
 * safe to unbind from the GTT or access from the CPU.
 */
static int
i915_gem_object_wait_rendering(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int ret;

        /* This function only exists to support waiting for existing rendering,
         * not for emitting required flushes.
         */
        BUG_ON((obj->write_domain & I915_GEM_GPU_DOMAINS) != 0);

        /* If there is rendering queued on the buffer being evicted, wait for
         * it.
         */
        if (obj_priv->active) {
#if WATCH_BUF
                DRM_INFO("%s: object %p wait for seqno %08x\n",
                          __func__, obj, obj_priv->last_rendering_seqno);
#endif
                ret = i915_wait_request(dev, obj_priv->last_rendering_seqno);
                if (ret != 0)
                        return ret;
        }

        return 0;
}

/**
 * Unbinds an object from the GTT aperture.
 */
int
i915_gem_object_unbind(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int ret = 0;

#if WATCH_BUF
        DRM_INFO("%s:%d %p\n", __func__, __LINE__, obj);
        DRM_INFO("gtt_space %p\n", obj_priv->gtt_space);
#endif
        if (obj_priv->gtt_space == NULL)
                return 0;

        if (obj_priv->pin_count != 0) {
                DRM_ERROR("Attempting to unbind pinned buffer\n");
                return -EINVAL;
        }

        /* blow away mappings if mapped through GTT */
        i915_gem_release_mmap(obj);

        if (obj_priv->fence_reg != I915_FENCE_REG_NONE)
                i915_gem_clear_fence_reg(obj);

        /* Move the object to the CPU domain to ensure that
         * any possible CPU writes while it's not in the GTT
         * are flushed when we go to remap it. This will
         * also ensure that all pending GPU writes are finished
         * before we unbind.
         */
        ret = i915_gem_object_set_to_cpu_domain(obj, 1);
        if (ret) {
                if (ret != -ERESTARTSYS)
                        DRM_ERROR("set_domain failed: %d\n", ret);
                return ret;
        }

        BUG_ON(obj_priv->active);

        if (obj_priv->agp_mem != NULL) {
                drm_unbind_agp(obj_priv->agp_mem);
                drm_free_agp(obj_priv->agp_mem, obj->size / PAGE_SIZE);
                obj_priv->agp_mem = NULL;
        }

        i915_gem_object_put_pages(obj);

        if (obj_priv->gtt_space) {
                atomic_dec(&dev->gtt_count);
                atomic_sub(obj->size, &dev->gtt_memory);

                drm_mm_put_block(obj_priv->gtt_space);
                obj_priv->gtt_space = NULL;
        }

        /* Remove ourselves from the LRU list if present. */
        if (!list_empty(&obj_priv->list))
                list_del_init(&obj_priv->list);

        return 0;
}

static int
i915_gem_evict_something(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;
        int ret = 0;

        for (;;) {
                /* If there's an inactive buffer available now, grab it
                 * and be done.
                 */
                if (!list_empty(&dev_priv->mm.inactive_list)) {
                        obj_priv = list_first_entry(&dev_priv->mm.inactive_list,
                                                    struct drm_i915_gem_object,
                                                    list);
                        obj = obj_priv->obj;
                        BUG_ON(obj_priv->pin_count != 0);
#if WATCH_LRU
                        DRM_INFO("%s: evicting %p\n", __func__, obj);
#endif
                        BUG_ON(obj_priv->active);

                        /* Wait on the rendering and unbind the buffer. */
                        ret = i915_gem_object_unbind(obj);
                        break;
                }

                /* If we didn't get anything, but the ring is still processing
                 * things, wait for one of those things to finish and hopefully
                 * leave us a buffer to evict.
                 */
                if (!list_empty(&dev_priv->mm.request_list)) {
                        struct drm_i915_gem_request *request;

                        request = list_first_entry(&dev_priv->mm.request_list,
                                                   struct drm_i915_gem_request,
                                                   list);

                        ret = i915_wait_request(dev, request->seqno);
                        if (ret)
                                break;

                        /* if waiting caused an object to become inactive,
                         * then loop around and wait for it. Otherwise, we
                         * assume that waiting freed and unbound something,
                         * so there should now be some space in the GTT
                         */
                        if (!list_empty(&dev_priv->mm.inactive_list))
                                continue;
                        break;
                }

                /* If we didn't have anything on the request list but there
                 * are buffers awaiting a flush, emit one and try again.
                 * When we wait on it, those buffers waiting for that flush
                 * will get moved to inactive.
                 */
                if (!list_empty(&dev_priv->mm.flushing_list)) {
                        obj_priv = list_first_entry(&dev_priv->mm.flushing_list,
                                                    struct drm_i915_gem_object,
                                                    list);
                        obj = obj_priv->obj;

                        i915_gem_flush(dev,
                                       obj->write_domain,
                                       obj->write_domain);
                        i915_add_request(dev, NULL, obj->write_domain);

                        obj = NULL;
                        continue;
                }

                DRM_ERROR("inactive empty %d request empty %d "
                          "flushing empty %d\n",
                          list_empty(&dev_priv->mm.inactive_list),
                          list_empty(&dev_priv->mm.request_list),
                          list_empty(&dev_priv->mm.flushing_list));
                /* If we didn't do any of the above, there's nothing to be done
                 * and we just can't fit it in.
                 */
                return -ENOSPC;
        }
        return ret;
}

static int
i915_gem_evict_everything(struct drm_device *dev)
{
        int ret;

        for (;;) {
                ret = i915_gem_evict_something(dev);
                if (ret != 0)
                        break;
        }
        if (ret == -ENOSPC)
                return 0;
        return ret;
}

int
i915_gem_object_get_pages(struct drm_gem_object *obj)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int page_count, i;
        struct address_space *mapping;
        struct inode *inode;
        struct page *page;
        int ret;

        if (obj_priv->pages_refcount++ != 0)
                return 0;

        /* Get the list of pages out of our struct file.  They'll be pinned
         * at this point until we release them.
         */
        page_count = obj->size / PAGE_SIZE;
        BUG_ON(obj_priv->pages != NULL);
        obj_priv->pages = drm_calloc_large(page_count, sizeof(struct page *));
        if (obj_priv->pages == NULL) {
                DRM_ERROR("Faled to allocate page list\n");
                obj_priv->pages_refcount--;
                return -ENOMEM;
        }

        inode = obj->filp->f_path.dentry->d_inode;
        mapping = inode->i_mapping;
        for (i = 0; i < page_count; i++) {
                page = read_mapping_page(mapping, i, NULL);
                if (IS_ERR(page)) {
                        ret = PTR_ERR(page);
                        DRM_ERROR("read_mapping_page failed: %d\n", ret);
                        i915_gem_object_put_pages(obj);
                        return ret;
                }
                obj_priv->pages[i] = page;
        }

        if (obj_priv->tiling_mode != I915_TILING_NONE)
                i915_gem_object_do_bit_17_swizzle(obj);

        return 0;
}

static void i965_write_fence_reg(struct drm_i915_fence_reg *reg)
{
        struct drm_gem_object *obj = reg->obj;
        struct drm_device *dev = obj->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int regnum = obj_priv->fence_reg;
        uint64_t val;

        val = (uint64_t)((obj_priv->gtt_offset + obj->size - 4096) &
                    0xfffff000) << 32;
        val |= obj_priv->gtt_offset & 0xfffff000;
        val |= ((obj_priv->stride / 128) - 1) << I965_FENCE_PITCH_SHIFT;
        if (obj_priv->tiling_mode == I915_TILING_Y)
                val |= 1 << I965_FENCE_TILING_Y_SHIFT;
        val |= I965_FENCE_REG_VALID;

        I915_WRITE64(FENCE_REG_965_0 + (regnum * 8), val);
}

static void i915_write_fence_reg(struct drm_i915_fence_reg *reg)
{
        struct drm_gem_object *obj = reg->obj;
        struct drm_device *dev = obj->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int regnum = obj_priv->fence_reg;
        int tile_width;
        uint32_t fence_reg, val;
        uint32_t pitch_val;

        if ((obj_priv->gtt_offset & ~I915_FENCE_START_MASK) ||
            (obj_priv->gtt_offset & (obj->size - 1))) {
                WARN(1, "%s: object 0x%08x not 1M or size (0x%zx) aligned\n",
                     __func__, obj_priv->gtt_offset, obj->size);
                return;
        }

        if (obj_priv->tiling_mode == I915_TILING_Y &&
            HAS_128_BYTE_Y_TILING(dev))
                tile_width = 128;
        else
                tile_width = 512;

        /* Note: pitch better be a power of two tile widths */
        pitch_val = obj_priv->stride / tile_width;
        pitch_val = ffs(pitch_val) - 1;

        val = obj_priv->gtt_offset;
        if (obj_priv->tiling_mode == I915_TILING_Y)
                val |= 1 << I830_FENCE_TILING_Y_SHIFT;
        val |= I915_FENCE_SIZE_BITS(obj->size);
        val |= pitch_val << I830_FENCE_PITCH_SHIFT;
        val |= I830_FENCE_REG_VALID;

        if (regnum < 8)
                fence_reg = FENCE_REG_830_0 + (regnum * 4);
        else
                fence_reg = FENCE_REG_945_8 + ((regnum - 8) * 4);
        I915_WRITE(fence_reg, val);
}

static void i830_write_fence_reg(struct drm_i915_fence_reg *reg)
{
        struct drm_gem_object *obj = reg->obj;
        struct drm_device *dev = obj->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int regnum = obj_priv->fence_reg;
        uint32_t val;
        uint32_t pitch_val;
        uint32_t fence_size_bits;

        if ((obj_priv->gtt_offset & ~I830_FENCE_START_MASK) ||
            (obj_priv->gtt_offset & (obj->size - 1))) {
                WARN(1, "%s: object 0x%08x not 512K or size aligned\n",
                     __func__, obj_priv->gtt_offset);
                return;
        }

        pitch_val = obj_priv->stride / 128;
        pitch_val = ffs(pitch_val) - 1;
        WARN_ON(pitch_val > I830_FENCE_MAX_PITCH_VAL);

        val = obj_priv->gtt_offset;
        if (obj_priv->tiling_mode == I915_TILING_Y)
                val |= 1 << I830_FENCE_TILING_Y_SHIFT;
        fence_size_bits = I830_FENCE_SIZE_BITS(obj->size);
        WARN_ON(fence_size_bits & ~0x00000f00);
        val |= fence_size_bits;
        val |= pitch_val << I830_FENCE_PITCH_SHIFT;
        val |= I830_FENCE_REG_VALID;

        I915_WRITE(FENCE_REG_830_0 + (regnum * 4), val);
}

/**
 * i915_gem_object_get_fence_reg - set up a fence reg for an object
 * @obj: object to map through a fence reg
 *
 * When mapping objects through the GTT, userspace wants to be able to write
 * to them without having to worry about swizzling if the object is tiled.
 *
 * This function walks the fence regs looking for a free one for @obj,
 * stealing one if it can't find any.
 *
 * It then sets up the reg based on the object's properties: address, pitch
 * and tiling format.
 */
int
i915_gem_object_get_fence_reg(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        struct drm_i915_fence_reg *reg = NULL;
        struct drm_i915_gem_object *old_obj_priv = NULL;
        int i, ret, avail;

        /* Just update our place in the LRU if our fence is getting used. */
        if (obj_priv->fence_reg != I915_FENCE_REG_NONE) {
                list_move_tail(&obj_priv->fence_list, &dev_priv->mm.fence_list);
                return 0;
        }

        switch (obj_priv->tiling_mode) {
        case I915_TILING_NONE:
                WARN(1, "allocating a fence for non-tiled object?\n");
                break;
        case I915_TILING_X:
                if (!obj_priv->stride)
                        return -EINVAL;
                WARN((obj_priv->stride & (512 - 1)),
                     "object 0x%08x is X tiled but has non-512B pitch\n",
                     obj_priv->gtt_offset);
                break;
        case I915_TILING_Y:
                if (!obj_priv->stride)
                        return -EINVAL;
                WARN((obj_priv->stride & (128 - 1)),
                     "object 0x%08x is Y tiled but has non-128B pitch\n",
                     obj_priv->gtt_offset);
                break;
        }

        /* First try to find a free reg */
        avail = 0;
        for (i = dev_priv->fence_reg_start; i < dev_priv->num_fence_regs; i++) {
                reg = &dev_priv->fence_regs[i];
                if (!reg->obj)
                        break;

                old_obj_priv = reg->obj->driver_private;
                if (!old_obj_priv->pin_count)
                    avail++;
        }

        /* None available, try to steal one or wait for a user to finish */
        if (i == dev_priv->num_fence_regs) {
                struct drm_gem_object *old_obj = NULL;

                if (avail == 0)
                        return -ENOSPC;

                list_for_each_entry(old_obj_priv, &dev_priv->mm.fence_list,
                                    fence_list) {
                        old_obj = old_obj_priv->obj;

                        if (old_obj_priv->pin_count)
                                continue;

                        /* Take a reference, as otherwise the wait_rendering
                         * below may cause the object to get freed out from
                         * under us.
                         */
                        drm_gem_object_reference(old_obj);

                        /* i915 uses fences for GPU access to tiled buffers */
                        if (IS_I965G(dev) || !old_obj_priv->active)
                                break;

                        /* This brings the object to the head of the LRU if it
                         * had been written to.  The only way this should
                         * result in us waiting longer than the expected
                         * optimal amount of time is if there was a
                         * fence-using buffer later that was read-only.
                         */
                        i915_gem_object_flush_gpu_write_domain(old_obj);
                        ret = i915_gem_object_wait_rendering(old_obj);
                        if (ret != 0) {
                                drm_gem_object_unreference(old_obj);
                                return ret;
                        }

                        break;
                }

                /*
                 * Zap this virtual mapping so we can set up a fence again
                 * for this object next time we need it.
                 */
                i915_gem_release_mmap(old_obj);

                i = old_obj_priv->fence_reg;
                reg = &dev_priv->fence_regs[i];

                old_obj_priv->fence_reg = I915_FENCE_REG_NONE;
                list_del_init(&old_obj_priv->fence_list);

                drm_gem_object_unreference(old_obj);
        }

        obj_priv->fence_reg = i;
        list_add_tail(&obj_priv->fence_list, &dev_priv->mm.fence_list);

        reg->obj = obj;

        if (IS_I965G(dev))
                i965_write_fence_reg(reg);
        else if (IS_I9XX(dev))
                i915_write_fence_reg(reg);
        else
                i830_write_fence_reg(reg);

        return 0;
}

/**
 * i915_gem_clear_fence_reg - clear out fence register info
 * @obj: object to clear
 *
 * Zeroes out the fence register itself and clears out the associated
 * data structures in dev_priv and obj_priv.
 */
static void
i915_gem_clear_fence_reg(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;

        if (IS_I965G(dev))
                I915_WRITE64(FENCE_REG_965_0 + (obj_priv->fence_reg * 8), 0);
        else {
                uint32_t fence_reg;

                if (obj_priv->fence_reg < 8)
                        fence_reg = FENCE_REG_830_0 + obj_priv->fence_reg * 4;
                else
                        fence_reg = FENCE_REG_945_8 + (obj_priv->fence_reg -
                                                       8) * 4;

                I915_WRITE(fence_reg, 0);
        }

        dev_priv->fence_regs[obj_priv->fence_reg].obj = NULL;
        obj_priv->fence_reg = I915_FENCE_REG_NONE;
        list_del_init(&obj_priv->fence_list);
}

/**
 * i915_gem_object_put_fence_reg - waits on outstanding fenced access
 * to the buffer to finish, and then resets the fence register.
 * @obj: tiled object holding a fence register.
 *
 * Zeroes out the fence register itself and clears out the associated
 * data structures in dev_priv and obj_priv.
 */
int
i915_gem_object_put_fence_reg(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;

        if (obj_priv->fence_reg == I915_FENCE_REG_NONE)
                return 0;

        /* On the i915, GPU access to tiled buffers is via a fence,
         * therefore we must wait for any outstanding access to complete
         * before clearing the fence.
         */
        if (!IS_I965G(dev)) {
                int ret;

                i915_gem_object_flush_gpu_write_domain(obj);
                i915_gem_object_flush_gtt_write_domain(obj);
                ret = i915_gem_object_wait_rendering(obj);
                if (ret != 0)
                        return ret;
        }

        i915_gem_clear_fence_reg (obj);

        return 0;
}

/**
 * Finds free space in the GTT aperture and binds the object there.
 */
static int
i915_gem_object_bind_to_gtt(struct drm_gem_object *obj, unsigned alignment)
{
        struct drm_device *dev = obj->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        struct drm_mm_node *free_space;
        int page_count, ret;

        if (dev_priv->mm.suspended)
                return -EBUSY;
        if (alignment == 0)
                alignment = i915_gem_get_gtt_alignment(obj);
        if (alignment & (i915_gem_get_gtt_alignment(obj) - 1)) {
                DRM_ERROR("Invalid object alignment requested %u\n", alignment);
                return -EINVAL;
        }

 search_free:
        free_space = drm_mm_search_free(&dev_priv->mm.gtt_space,
                                        obj->size, alignment, 0);
        if (free_space != NULL) {
                obj_priv->gtt_space = drm_mm_get_block(free_space, obj->size,
                                                       alignment);
                if (obj_priv->gtt_space != NULL) {
                        obj_priv->gtt_space->private = obj;
                        obj_priv->gtt_offset = obj_priv->gtt_space->start;
                }
        }
        if (obj_priv->gtt_space == NULL) {
                bool lists_empty;

                /* If the gtt is empty and we're still having trouble
                 * fitting our object in, we're out of memory.
                 */
#if WATCH_LRU
                DRM_INFO("%s: GTT full, evicting something\n", __func__);
#endif
                spin_lock(&dev_priv->mm.active_list_lock);
                lists_empty = (list_empty(&dev_priv->mm.inactive_list) &&
                               list_empty(&dev_priv->mm.flushing_list) &&
                               list_empty(&dev_priv->mm.active_list));
                spin_unlock(&dev_priv->mm.active_list_lock);
                if (lists_empty) {
                        DRM_ERROR("GTT full, but LRU list empty\n");
                        return -ENOSPC;
                }

                ret = i915_gem_evict_something(dev);
                if (ret != 0) {
                        if (ret != -ERESTARTSYS)
                                DRM_ERROR("Failed to evict a buffer %d\n", ret);
                        return ret;
                }
                goto search_free;
        }

#if WATCH_BUF
        DRM_INFO("Binding object of size %zd at 0x%08x\n",
                 obj->size, obj_priv->gtt_offset);
#endif
        ret = i915_gem_object_get_pages(obj);
        if (ret) {
                drm_mm_put_block(obj_priv->gtt_space);
                obj_priv->gtt_space = NULL;
                return ret;
        }

        page_count = obj->size / PAGE_SIZE;
        /* Create an AGP memory structure pointing at our pages, and bind it
         * into the GTT.
         */
        obj_priv->agp_mem = drm_agp_bind_pages(dev,
                                               obj_priv->pages,
                                               page_count,
                                               obj_priv->gtt_offset,
                                               obj_priv->agp_type);
        if (obj_priv->agp_mem == NULL) {
                i915_gem_object_put_pages(obj);
                drm_mm_put_block(obj_priv->gtt_space);
                obj_priv->gtt_space = NULL;
                return -ENOMEM;
        }
        atomic_inc(&dev->gtt_count);
        atomic_add(obj->size, &dev->gtt_memory);

        /* Assert that the object is not currently in any GPU domain. As it
         * wasn't in the GTT, there shouldn't be any way it could have been in
         * a GPU cache
         */
        BUG_ON(obj->read_domains & I915_GEM_GPU_DOMAINS);
        BUG_ON(obj->write_domain & I915_GEM_GPU_DOMAINS);

        return 0;
}

void
i915_gem_clflush_object(struct drm_gem_object *obj)
{
        struct drm_i915_gem_object      *obj_priv = obj->driver_private;

        /* If we don't have a page list set up, then we're not pinned
         * to GPU, and we can ignore the cache flush because it'll happen
         * again at bind time.
         */
        if (obj_priv->pages == NULL)
                return;

        drm_clflush_pages(obj_priv->pages, obj->size / PAGE_SIZE);
}

/** Flushes any GPU write domain for the object if it's dirty. */
static void
i915_gem_object_flush_gpu_write_domain(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        uint32_t seqno;

        if ((obj->write_domain & I915_GEM_GPU_DOMAINS) == 0)
                return;

        /* Queue the GPU write cache flushing we need. */
        i915_gem_flush(dev, 0, obj->write_domain);
        seqno = i915_add_request(dev, NULL, obj->write_domain);
        obj->write_domain = 0;
        i915_gem_object_move_to_active(obj, seqno);
}

/** Flushes the GTT write domain for the object if it's dirty. */
static void
i915_gem_object_flush_gtt_write_domain(struct drm_gem_object *obj)
{
        if (obj->write_domain != I915_GEM_DOMAIN_GTT)
                return;

        /* No actual flushing is required for the GTT write domain.   Writes
         * to it immediately go to main memory as far as we know, so there's
         * no chipset flush.  It also doesn't land in render cache.
         */
        obj->write_domain = 0;
}

/** Flushes the CPU write domain for the object if it's dirty. */
static void
i915_gem_object_flush_cpu_write_domain(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;

        if (obj->write_domain != I915_GEM_DOMAIN_CPU)
                return;

        i915_gem_clflush_object(obj);
        drm_agp_chipset_flush(dev);
        obj->write_domain = 0;
}

/**
 * Moves a single object to the GTT read, and possibly write domain.
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
int
i915_gem_object_set_to_gtt_domain(struct drm_gem_object *obj, int write)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int ret;

        /* Not valid to be called on unbound objects. */
        if (obj_priv->gtt_space == NULL)
                return -EINVAL;

        i915_gem_object_flush_gpu_write_domain(obj);
        /* Wait on any GPU rendering and flushing to occur. */
        ret = i915_gem_object_wait_rendering(obj);
        if (ret != 0)
                return ret;

        /* If we're writing through the GTT domain, then CPU and GPU caches
         * will need to be invalidated at next use.
         */
        if (write)
                obj->read_domains &= I915_GEM_DOMAIN_GTT;

        i915_gem_object_flush_cpu_write_domain(obj);

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->write_domain & ~I915_GEM_DOMAIN_GTT) != 0);
        obj->read_domains |= I915_GEM_DOMAIN_GTT;
        if (write) {
                obj->write_domain = I915_GEM_DOMAIN_GTT;
                obj_priv->dirty = 1;
        }

        return 0;
}

/**
 * Moves a single object to the CPU read, and possibly write domain.
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
static int
i915_gem_object_set_to_cpu_domain(struct drm_gem_object *obj, int write)
{
        int ret;

        i915_gem_object_flush_gpu_write_domain(obj);
        /* Wait on any GPU rendering and flushing to occur. */
        ret = i915_gem_object_wait_rendering(obj);
        if (ret != 0)
                return ret;

        i915_gem_object_flush_gtt_write_domain(obj);

        /* If we have a partially-valid cache of the object in the CPU,
         * finish invalidating it and free the per-page flags.
         */
        i915_gem_object_set_to_full_cpu_read_domain(obj);

        /* Flush the CPU cache if it's still invalid. */
        if ((obj->read_domains & I915_GEM_DOMAIN_CPU) == 0) {
                i915_gem_clflush_object(obj);

                obj->read_domains |= I915_GEM_DOMAIN_CPU;
        }

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->write_domain & ~I915_GEM_DOMAIN_CPU) != 0);

        /* If we're writing through the CPU, then the GPU read domains will
         * need to be invalidated at next use.
         */
        if (write) {
                obj->read_domains &= I915_GEM_DOMAIN_CPU;
                obj->write_domain = I915_GEM_DOMAIN_CPU;
        }

        return 0;
}

/*
 * Set the next domain for the specified object. This
 * may not actually perform the necessary flushing/invaliding though,
 * as that may want to be batched with other set_domain operations
 *
 * This is (we hope) the only really tricky part of gem. The goal
 * is fairly simple -- track which caches hold bits of the object
 * and make sure they remain coherent. A few concrete examples may
 * help to explain how it works. For shorthand, we use the notation
 * (read_domains, write_domain), e.g. (CPU, CPU) to indicate the
 * a pair of read and write domain masks.
 *
 * Case 1: the batch buffer
 *
 *      1. Allocated
 *      2. Written by CPU
 *      3. Mapped to GTT
 *      4. Read by GPU
 *      5. Unmapped from GTT
 *      6. Freed
 *
 *      Let's take these a step at a time
 *
 *      1. Allocated
 *              Pages allocated from the kernel may still have
 *              cache contents, so we set them to (CPU, CPU) always.
 *      2. Written by CPU (using pwrite)
 *              The pwrite function calls set_domain (CPU, CPU) and
 *              this function does nothing (as nothing changes)
 *      3. Mapped by GTT
 *              This function asserts that the object is not
 *              currently in any GPU-based read or write domains
 *      4. Read by GPU
 *              i915_gem_execbuffer calls set_domain (COMMAND, 0).
 *              As write_domain is zero, this function adds in the
 *              current read domains (CPU+COMMAND, 0).
 *              flush_domains is set to CPU.
 *              invalidate_domains is set to COMMAND
 *              clflush is run to get data out of the CPU caches
 *              then i915_dev_set_domain calls i915_gem_flush to
 *              emit an MI_FLUSH and drm_agp_chipset_flush
 *      5. Unmapped from GTT
 *              i915_gem_object_unbind calls set_domain (CPU, CPU)
 *              flush_domains and invalidate_domains end up both zero
 *              so no flushing/invalidating happens
 *      6. Freed
 *              yay, done
 *
 * Case 2: The shared render buffer
 *
 *      1. Allocated
 *      2. Mapped to GTT
 *      3. Read/written by GPU
 *      4. set_domain to (CPU,CPU)
 *      5. Read/written by CPU
 *      6. Read/written by GPU
 *
 *      1. Allocated
 *              Same as last example, (CPU, CPU)
 *      2. Mapped to GTT
 *              Nothing changes (assertions find that it is not in the GPU)
 *      3. Read/written by GPU
 *              execbuffer calls set_domain (RENDER, RENDER)
 *              flush_domains gets CPU
 *              invalidate_domains gets GPU
 *              clflush (obj)
 *              MI_FLUSH and drm_agp_chipset_flush
 *      4. set_domain (CPU, CPU)
 *              flush_domains gets GPU
 *              invalidate_domains gets CPU
 *              wait_rendering (obj) to make sure all drawing is complete.
 *              This will include an MI_FLUSH to get the data from GPU
 *              to memory
 *              clflush (obj) to invalidate the CPU cache
 *              Another MI_FLUSH in i915_gem_flush (eliminate this somehow?)
 *      5. Read/written by CPU
 *              cache lines are loaded and dirtied
 *      6. Read written by GPU
 *              Same as last GPU access
 *
 * Case 3: The constant buffer
 *
 *      1. Allocated
 *      2. Written by CPU
 *      3. Read by GPU
 *      4. Updated (written) by CPU again
 *      5. Read by GPU
 *
 *      1. Allocated
 *              (CPU, CPU)
 *      2. Written by CPU
 *              (CPU, CPU)
 *      3. Read by GPU
 *              (CPU+RENDER, 0)
 *              flush_domains = CPU
 *              invalidate_domains = RENDER
 *              clflush (obj)
 *              MI_FLUSH
 *              drm_agp_chipset_flush
 *      4. Updated (written) by CPU again
 *              (CPU, CPU)
 *              flush_domains = 0 (no previous write domain)
 *              invalidate_domains = 0 (no new read domains)
 *      5. Read by GPU
 *              (CPU+RENDER, 0)
 *              flush_domains = CPU
 *              invalidate_domains = RENDER
 *              clflush (obj)
 *              MI_FLUSH
 *              drm_agp_chipset_flush
 */
static void
i915_gem_object_set_to_gpu_domain(struct drm_gem_object *obj)
{
        struct drm_device               *dev = obj->dev;
        struct drm_i915_gem_object      *obj_priv = obj->driver_private;
        uint32_t                        invalidate_domains = 0;
        uint32_t                        flush_domains = 0;

        BUG_ON(obj->pending_read_domains & I915_GEM_DOMAIN_CPU);
        BUG_ON(obj->pending_write_domain == I915_GEM_DOMAIN_CPU);

        intel_mark_busy(dev, obj);

#if WATCH_BUF
        DRM_INFO("%s: object %p read %08x -> %08x write %08x -> %08x\n",
                 __func__, obj,
                 obj->read_domains, obj->pending_read_domains,
                 obj->write_domain, obj->pending_write_domain);
#endif
        /*
         * If the object isn't moving to a new write domain,
         * let the object stay in multiple read domains
         */
        if (obj->pending_write_domain == 0)
                obj->pending_read_domains |= obj->read_domains;
        else
                obj_priv->dirty = 1;

        /*
         * Flush the current write domain if
         * the new read domains don't match. Invalidate
         * any read domains which differ from the old
         * write domain
         */
        if (obj->write_domain &&
            obj->write_domain != obj->pending_read_domains) {
                flush_domains |= obj->write_domain;
                invalidate_domains |=
                        obj->pending_read_domains & ~obj->write_domain;
        }
        /*
         * Invalidate any read caches which may have
         * stale data. That is, any new read domains.
         */
        invalidate_domains |= obj->pending_read_domains & ~obj->read_domains;
        if ((flush_domains | invalidate_domains) & I915_GEM_DOMAIN_CPU) {
#if WATCH_BUF
                DRM_INFO("%s: CPU domain flush %08x invalidate %08x\n",
                         __func__, flush_domains, invalidate_domains);
#endif
                i915_gem_clflush_object(obj);
        }

        /* The actual obj->write_domain will be updated with
         * pending_write_domain after we emit the accumulated flush for all
         * of our domain changes in execbuffers (which clears objects'
         * write_domains).  So if we have a current write domain that we
         * aren't changing, set pending_write_domain to that.
         */
        if (flush_domains == 0 && obj->pending_write_domain == 0)
                obj->pending_write_domain = obj->write_domain;
        obj->read_domains = obj->pending_read_domains;

        dev->invalidate_domains |= invalidate_domains;
        dev->flush_domains |= flush_domains;
#if WATCH_BUF
        DRM_INFO("%s: read %08x write %08x invalidate %08x flush %08x\n",
                 __func__,
                 obj->read_domains, obj->write_domain,
                 dev->invalidate_domains, dev->flush_domains);
#endif
}

/**
 * Moves the object from a partially CPU read to a full one.
 *
 * Note that this only resolves i915_gem_object_set_cpu_read_domain_range(),
 * and doesn't handle transitioning from !(read_domains & I915_GEM_DOMAIN_CPU).
 */
static void
i915_gem_object_set_to_full_cpu_read_domain(struct drm_gem_object *obj)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;

        if (!obj_priv->page_cpu_valid)
                return;

        /* If we're partially in the CPU read domain, finish moving it in.
         */
        if (obj->read_domains & I915_GEM_DOMAIN_CPU) {
                int i;

                for (i = 0; i <= (obj->size - 1) / PAGE_SIZE; i++) {
                        if (obj_priv->page_cpu_valid[i])
                                continue;
                        drm_clflush_pages(obj_priv->pages + i, 1);
                }
        }

        /* Free the page_cpu_valid mappings which are now stale, whether
         * or not we've got I915_GEM_DOMAIN_CPU.
         */
        kfree(obj_priv->page_cpu_valid);
        obj_priv->page_cpu_valid = NULL;
}

/**
 * Set the CPU read domain on a range of the object.
 *
 * The object ends up with I915_GEM_DOMAIN_CPU in its read flags although it's
 * not entirely valid.  The page_cpu_valid member of the object flags which
 * pages have been flushed, and will be respected by
 * i915_gem_object_set_to_cpu_domain() if it's called on to get a valid mapping
 * of the whole object.
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
static int
i915_gem_object_set_cpu_read_domain_range(struct drm_gem_object *obj,
                                          uint64_t offset, uint64_t size)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int i, ret;

        if (offset == 0 && size == obj->size)
                return i915_gem_object_set_to_cpu_domain(obj, 0);

        i915_gem_object_flush_gpu_write_domain(obj);
        /* Wait on any GPU rendering and flushing to occur. */
        ret = i915_gem_object_wait_rendering(obj);
        if (ret != 0)
                return ret;
        i915_gem_object_flush_gtt_write_domain(obj);

        /* If we're already fully in the CPU read domain, we're done. */
        if (obj_priv->page_cpu_valid == NULL &&
            (obj->read_domains & I915_GEM_DOMAIN_CPU) != 0)
                return 0;

        /* Otherwise, create/clear the per-page CPU read domain flag if we're
         * newly adding I915_GEM_DOMAIN_CPU
         */
        if (obj_priv->page_cpu_valid == NULL) {
                obj_priv->page_cpu_valid = kzalloc(obj->size / PAGE_SIZE,
                                                   GFP_KERNEL);
                if (obj_priv->page_cpu_valid == NULL)
                        return -ENOMEM;
        } else if ((obj->read_domains & I915_GEM_DOMAIN_CPU) == 0)
                memset(obj_priv->page_cpu_valid, 0, obj->size / PAGE_SIZE);

        /* Flush the cache on any pages that are still invalid from the CPU's
         * perspective.
         */
        for (i = offset / PAGE_SIZE; i <= (offset + size - 1) / PAGE_SIZE;
             i++) {
                if (obj_priv->page_cpu_valid[i])
                        continue;

                drm_clflush_pages(obj_priv->pages + i, 1);

                obj_priv->page_cpu_valid[i] = 1;
        }

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->write_domain & ~I915_GEM_DOMAIN_CPU) != 0);

        obj->read_domains |= I915_GEM_DOMAIN_CPU;

        return 0;
}

/**
 * Pin an object to the GTT and evaluate the relocations landing in it.
 */
static int
i915_gem_object_pin_and_relocate(struct drm_gem_object *obj,
                                 struct drm_file *file_priv,
                                 struct drm_i915_gem_exec_object *entry,
                                 struct drm_i915_gem_relocation_entry *relocs)
{
        struct drm_device *dev = obj->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int i, ret;
        void __iomem *reloc_page;

        /* Choose the GTT offset for our buffer and put it there. */
        ret = i915_gem_object_pin(obj, (uint32_t) entry->alignment);
        if (ret)
                return ret;

        entry->offset = obj_priv->gtt_offset;

        /* Apply the relocations, using the GTT aperture to avoid cache
         * flushing requirements.
         */
        for (i = 0; i < entry->relocation_count; i++) {
                struct drm_i915_gem_relocation_entry *reloc= &relocs[i];
                struct drm_gem_object *target_obj;
                struct drm_i915_gem_object *target_obj_priv;
                uint32_t reloc_val, reloc_offset;
                uint32_t __iomem *reloc_entry;

                target_obj = drm_gem_object_lookup(obj->dev, file_priv,
                                                   reloc->target_handle);
                if (target_obj == NULL) {
                        i915_gem_object_unpin(obj);
                        return -EBADF;
                }
                target_obj_priv = target_obj->driver_private;

                /* The target buffer should have appeared before us in the
                 * exec_object list, so it should have a GTT space bound by now.
                 */
                if (target_obj_priv->gtt_space == NULL) {
                        DRM_ERROR("No GTT space found for object %d\n",
                                  reloc->target_handle);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }

                if (reloc->offset > obj->size - 4) {
                        DRM_ERROR("Relocation beyond object bounds: "
                                  "obj %p target %d offset %d size %d.\n",
                                  obj, reloc->target_handle,
                                  (int) reloc->offset, (int) obj->size);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }
                if (reloc->offset & 3) {
                        DRM_ERROR("Relocation not 4-byte aligned: "
                                  "obj %p target %d offset %d.\n",
                                  obj, reloc->target_handle,
                                  (int) reloc->offset);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }

                if (reloc->write_domain & I915_GEM_DOMAIN_CPU ||
                    reloc->read_domains & I915_GEM_DOMAIN_CPU) {
                        DRM_ERROR("reloc with read/write CPU domains: "
                                  "obj %p target %d offset %d "
                                  "read %08x write %08x",
                                  obj, reloc->target_handle,
                                  (int) reloc->offset,
                                  reloc->read_domains,
                                  reloc->write_domain);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }

                if (reloc->write_domain && target_obj->pending_write_domain &&
                    reloc->write_domain != target_obj->pending_write_domain) {
                        DRM_ERROR("Write domain conflict: "
                                  "obj %p target %d offset %d "
                                  "new %08x old %08x\n",
                                  obj, reloc->target_handle,
                                  (int) reloc->offset,
                                  reloc->write_domain,
                                  target_obj->pending_write_domain);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }

#if WATCH_RELOC
                DRM_INFO("%s: obj %p offset %08x target %d "
                         "read %08x write %08x gtt %08x "
                         "presumed %08x delta %08x\n",
                         __func__,
                         obj,
                         (int) reloc->offset,
                         (int) reloc->target_handle,
                         (int) reloc->read_domains,
                         (int) reloc->write_domain,
                         (int) target_obj_priv->gtt_offset,
                         (int) reloc->presumed_offset,
                         reloc->delta);
#endif

                target_obj->pending_read_domains |= reloc->read_domains;
                target_obj->pending_write_domain |= reloc->write_domain;

                /* If the relocation already has the right value in it, no
                 * more work needs to be done.
                 */
                if (target_obj_priv->gtt_offset == reloc->presumed_offset) {
                        drm_gem_object_unreference(target_obj);
                        continue;
                }

                ret = i915_gem_object_set_to_gtt_domain(obj, 1);
                if (ret != 0) {
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }

                /* Map the page containing the relocation we're going to
                 * perform.
                 */
                reloc_offset = obj_priv->gtt_offset + reloc->offset;
                reloc_page = io_mapping_map_atomic_wc(dev_priv->mm.gtt_mapping,
                                                      (reloc_offset &
                                                       ~(PAGE_SIZE - 1)));
                reloc_entry = (uint32_t __iomem *)(reloc_page +
                                                   (reloc_offset & (PAGE_SIZE - 1)));
                reloc_val = target_obj_priv->gtt_offset + reloc->delta;

#if WATCH_BUF
                DRM_INFO("Applied relocation: %p@0x%08x %08x -> %08x\n",
                          obj, (unsigned int) reloc->offset,
                          readl(reloc_entry), reloc_val);
#endif
                writel(reloc_val, reloc_entry);
                io_mapping_unmap_atomic(reloc_page);

                /* The updated presumed offset for this entry will be
                 * copied back out to the user.
                 */
                reloc->presumed_offset = target_obj_priv->gtt_offset;

                drm_gem_object_unreference(target_obj);
        }

#if WATCH_BUF
        if (0)
                i915_gem_dump_object(obj, 128, __func__, ~0);
#endif
        return 0;
}

/** Dispatch a batchbuffer to the ring
 */
static int
i915_dispatch_gem_execbuffer(struct drm_device *dev,
                              struct drm_i915_gem_execbuffer *exec,
                              struct drm_clip_rect *cliprects,
                              uint64_t exec_offset)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        int nbox = exec->num_cliprects;
        int i = 0, count;
        uint32_t exec_start, exec_len;
        RING_LOCALS;

        exec_start = (uint32_t) exec_offset + exec->batch_start_offset;
        exec_len = (uint32_t) exec->batch_len;

        count = nbox ? nbox : 1;

        for (i = 0; i < count; i++) {
                if (i < nbox) {
                        int ret = i915_emit_box(dev, cliprects, i,
                                                exec->DR1, exec->DR4);
                        if (ret)
                                return ret;
                }

                if (IS_I830(dev) || IS_845G(dev)) {
                        BEGIN_LP_RING(4);
                        OUT_RING(MI_BATCH_BUFFER);
                        OUT_RING(exec_start | MI_BATCH_NON_SECURE);
                        OUT_RING(exec_start + exec_len - 4);
                        OUT_RING(0);
                        ADVANCE_LP_RING();
                } else {
                        BEGIN_LP_RING(2);
                        if (IS_I965G(dev)) {
                                OUT_RING(MI_BATCH_BUFFER_START |
                                         (2 << 6) |
                                         MI_BATCH_NON_SECURE_I965);
                                OUT_RING(exec_start);
                        } else {
                                OUT_RING(MI_BATCH_BUFFER_START |
                                         (2 << 6));
                                OUT_RING(exec_start | MI_BATCH_NON_SECURE);
                        }
                        ADVANCE_LP_RING();
                }
        }

        /* XXX breadcrumb */
        return 0;
}

/* Throttle our rendering by waiting until the ring has completed our requests
 * emitted over 20 msec ago.
 *
 * Note that if we were to use the current jiffies each time around the loop,
 * we wouldn't escape the function with any frames outstanding if the time to
 * render a frame was over 20ms.
 *
 * This should get us reasonable parallelism between CPU and GPU but also
 * relatively low latency when blocking on a particular request to finish.
 */
static int
i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file_priv)
{
        struct drm_i915_file_private *i915_file_priv = file_priv->driver_priv;
        int ret = 0;
        unsigned long recent_enough = jiffies - msecs_to_jiffies(20);

        mutex_lock(&dev->struct_mutex);
        while (!list_empty(&i915_file_priv->mm.request_list)) {
                struct drm_i915_gem_request *request;

                request = list_first_entry(&i915_file_priv->mm.request_list,
                                           struct drm_i915_gem_request,
                                           client_list);

                if (time_after_eq(request->emitted_jiffies, recent_enough))
                        break;

                ret = i915_wait_request(dev, request->seqno);
                if (ret != 0)
                        break;
        }
        mutex_unlock(&dev->struct_mutex);

        return ret;
}

static int
i915_gem_get_relocs_from_user(struct drm_i915_gem_exec_object *exec_list,
                              uint32_t buffer_count,
                              struct drm_i915_gem_relocation_entry **relocs)
{
        uint32_t reloc_count = 0, reloc_index = 0, i;
        int ret;

        *relocs = NULL;
        for (i = 0; i < buffer_count; i++) {
                if (reloc_count + exec_list[i].relocation_count < reloc_count)
                        return -EINVAL;
                reloc_count += exec_list[i].relocation_count;
        }

        *relocs = drm_calloc_large(reloc_count, sizeof(**relocs));
        if (*relocs == NULL)
                return -ENOMEM;

        for (i = 0; i < buffer_count; i++) {
                struct drm_i915_gem_relocation_entry __user *user_relocs;

                user_relocs = (void __user *)(uintptr_t)exec_list[i].relocs_ptr;

                ret = copy_from_user(&(*relocs)[reloc_index],
                                     user_relocs,
                                     exec_list[i].relocation_count *
                                     sizeof(**relocs));
                if (ret != 0) {
                        drm_free_large(*relocs);
                        *relocs = NULL;
                        return -EFAULT;
                }

                reloc_index += exec_list[i].relocation_count;
        }

        return 0;
}

static int
i915_gem_put_relocs_to_user(struct drm_i915_gem_exec_object *exec_list,
                            uint32_t buffer_count,
                            struct drm_i915_gem_relocation_entry *relocs)
{
        uint32_t reloc_count = 0, i;
        int ret = 0;

        for (i = 0; i < buffer_count; i++) {
                struct drm_i915_gem_relocation_entry __user *user_relocs;
                int unwritten;

                user_relocs = (void __user *)(uintptr_t)exec_list[i].relocs_ptr;

                unwritten = copy_to_user(user_relocs,
                                         &relocs[reloc_count],
                                         exec_list[i].relocation_count *
                                         sizeof(*relocs));

                if (unwritten) {
                        ret = -EFAULT;
                        goto err;
                }

                reloc_count += exec_list[i].relocation_count;
        }

err:
        drm_free_large(relocs);

        return ret;
}

static int
i915_gem_check_execbuffer (struct drm_i915_gem_execbuffer *exec,
                           uint64_t exec_offset)
{
        uint32_t exec_start, exec_len;

        exec_start = (uint32_t) exec_offset + exec->batch_start_offset;
        exec_len = (uint32_t) exec->batch_len;

        if ((exec_start | exec_len) & 0x7)
                return -EINVAL;

        if (!exec_start)
                return -EINVAL;

        return 0;
}

int
i915_gem_execbuffer(struct drm_device *dev, void *data,
                    struct drm_file *file_priv)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_execbuffer *args = data;
        struct drm_i915_gem_exec_object *exec_list = NULL;
        struct drm_gem_object **object_list = NULL;
        struct drm_gem_object *batch_obj;
        struct drm_i915_gem_object *obj_priv;
        struct drm_clip_rect *cliprects = NULL;
        struct drm_i915_gem_relocation_entry *relocs;
        int ret, ret2, i, pinned = 0;
        uint64_t exec_offset;
        uint32_t seqno, flush_domains, reloc_index;
        int pin_tries;

#if WATCH_EXEC
        DRM_INFO("buffers_ptr %d buffer_count %d len %08x\n",
                  (int) args->buffers_ptr, args->buffer_count, args->batch_len);
#endif

        if (args->buffer_count < 1) {
                DRM_ERROR("execbuf with %d buffers\n", args->buffer_count);
                return -EINVAL;
        }
        /* Copy in the exec list from userland */
        exec_list = drm_calloc_large(sizeof(*exec_list), args->buffer_count);
        object_list = drm_calloc_large(sizeof(*object_list), args->buffer_count);
        if (exec_list == NULL || object_list == NULL) {
                DRM_ERROR("Failed to allocate exec or object list "
                          "for %d buffers\n",
                          args->buffer_count);
                ret = -ENOMEM;
                goto pre_mutex_err;
        }
        ret = copy_from_user(exec_list,
                             (struct drm_i915_relocation_entry __user *)
                             (uintptr_t) args->buffers_ptr,
                             sizeof(*exec_list) * args->buffer_count);
        if (ret != 0) {
                DRM_ERROR("copy %d exec entries failed %d\n",
                          args->buffer_count, ret);
                goto pre_mutex_err;
        }

        if (args->num_cliprects != 0) {
                cliprects = kcalloc(args->num_cliprects, sizeof(*cliprects),
                                    GFP_KERNEL);
                if (cliprects == NULL)
                        goto pre_mutex_err;

                ret = copy_from_user(cliprects,
                                     (struct drm_clip_rect __user *)
                                     (uintptr_t) args->cliprects_ptr,
                                     sizeof(*cliprects) * args->num_cliprects);
                if (ret != 0) {
                        DRM_ERROR("copy %d cliprects failed: %d\n",
                                  args->num_cliprects, ret);
                        goto pre_mutex_err;
                }
        }

        ret = i915_gem_get_relocs_from_user(exec_list, args->buffer_count,
                                            &relocs);
        if (ret != 0)
                goto pre_mutex_err;

        mutex_lock(&dev->struct_mutex);

        i915_verify_inactive(dev, __FILE__, __LINE__);

        if (atomic_read(&dev_priv->mm.wedged)) {
                DRM_ERROR("Execbuf while wedged\n");
                mutex_unlock(&dev->struct_mutex);
                ret = -EIO;
                goto pre_mutex_err;
        }

        if (dev_priv->mm.suspended) {
                DRM_ERROR("Execbuf while VT-switched.\n");
                mutex_unlock(&dev->struct_mutex);
                ret = -EBUSY;
                goto pre_mutex_err;
        }

        /* Look up object handles */
        for (i = 0; i < args->buffer_count; i++) {
                object_list[i] = drm_gem_object_lookup(dev, file_priv,
                                                       exec_list[i].handle);
                if (object_list[i] == NULL) {
                        DRM_ERROR("Invalid object handle %d at index %d\n",
                                   exec_list[i].handle, i);
                        ret = -EBADF;
                        goto err;
                }

                obj_priv = object_list[i]->driver_private;
                if (obj_priv->in_execbuffer) {
                        DRM_ERROR("Object %p appears more than once in object list\n",
                                   object_list[i]);
                        ret = -EBADF;
                        goto err;
                }
                obj_priv->in_execbuffer = true;
        }

        /* Pin and relocate */
        for (pin_tries = 0; ; pin_tries++) {
                ret = 0;
                reloc_index = 0;

                for (i = 0; i < args->buffer_count; i++) {
                        object_list[i]->pending_read_domains = 0;
                        object_list[i]->pending_write_domain = 0;
                        ret = i915_gem_object_pin_and_relocate(object_list[i],
                                                               file_priv,
                                                               &exec_list[i],
                                                               &relocs[reloc_index]);
                        if (ret)
                                break;
                        pinned = i + 1;
                        reloc_index += exec_list[i].relocation_count;
                }
                /* success */
                if (ret == 0)
                        break;

                /* error other than GTT full, or we've already tried again */
                if (ret != -ENOSPC || pin_tries >= 1) {
                        if (ret != -ERESTARTSYS)
                                DRM_ERROR("Failed to pin buffers %d\n", ret);
                        goto err;
                }

                /* unpin all of our buffers */
                for (i = 0; i < pinned; i++)
                        i915_gem_object_unpin(object_list[i]);
                pinned = 0;

                /* evict everyone we can from the aperture */
                ret = i915_gem_evict_everything(dev);
                if (ret)
                        goto err;
        }

        /* Set the pending read domains for the batch buffer to COMMAND */
        batch_obj = object_list[args->buffer_count-1];
        if (batch_obj->pending_write_domain) {
                DRM_ERROR("Attempting to use self-modifying batch buffer\n");
                ret = -EINVAL;
                goto err;
        }
        batch_obj->pending_read_domains |= I915_GEM_DOMAIN_COMMAND;

        /* Sanity check the batch buffer, prior to moving objects */
        exec_offset = exec_list[args->buffer_count - 1].offset;
        ret = i915_gem_check_execbuffer (args, exec_offset);
        if (ret != 0) {
                DRM_ERROR("execbuf with invalid offset/length\n");
                goto err;
        }

        i915_verify_inactive(dev, __FILE__, __LINE__);

        /* Zero the global flush/invalidate flags. These
         * will be modified as new domains are computed
         * for each object
         */
        dev->invalidate_domains = 0;
        dev->flush_domains = 0;

        for (i = 0; i < args->buffer_count; i++) {
                struct drm_gem_object *obj = object_list[i];

                /* Compute new gpu domains and update invalidate/flush */
                i915_gem_object_set_to_gpu_domain(obj);
        }

        i915_verify_inactive(dev, __FILE__, __LINE__);

        if (dev->invalidate_domains | dev->flush_domains) {
#if WATCH_EXEC
                DRM_INFO("%s: invalidate_domains %08x flush_domains %08x\n",
                          __func__,
                         dev->invalidate_domains,
                         dev->flush_domains);
#endif
                i915_gem_flush(dev,
                               dev->invalidate_domains,
                               dev->flush_domains);
                if (dev->flush_domains)
                        (void)i915_add_request(dev, file_priv,
                                               dev->flush_domains);
        }

        for (i = 0; i < args->buffer_count; i++) {
                struct drm_gem_object *obj = object_list[i];

                obj->write_domain = obj->pending_write_domain;
        }

        i915_verify_inactive(dev, __FILE__, __LINE__);

#if WATCH_COHERENCY
        for (i = 0; i < args->buffer_count; i++) {
                i915_gem_object_check_coherency(object_list[i],
                                                exec_list[i].handle);
        }
#endif

#if WATCH_EXEC
        i915_gem_dump_object(batch_obj,
                              args->batch_len,
                              __func__,
                              ~0);
#endif

        /* Exec the batchbuffer */
        ret = i915_dispatch_gem_execbuffer(dev, args, cliprects, exec_offset);
        if (ret) {
                DRM_ERROR("dispatch failed %d\n", ret);
                goto err;
        }

        /*
         * Ensure that the commands in the batch buffer are
         * finished before the interrupt fires
         */
        flush_domains = i915_retire_commands(dev);

        i915_verify_inactive(dev, __FILE__, __LINE__);

        /*
         * Get a seqno representing the execution of the current buffer,
         * which we can wait on.  We would like to mitigate these interrupts,
         * likely by only creating seqnos occasionally (so that we have
         * *some* interrupts representing completion of buffers that we can
         * wait on when trying to clear up gtt space).
         */
        seqno = i915_add_request(dev, file_priv, flush_domains);
        BUG_ON(seqno == 0);
        for (i = 0; i < args->buffer_count; i++) {
                struct drm_gem_object *obj = object_list[i];

                i915_gem_object_move_to_active(obj, seqno);
#if WATCH_LRU
                DRM_INFO("%s: move to exec list %p\n", __func__, obj);
#endif
        }
#if WATCH_LRU
        i915_dump_lru(dev, __func__);
#endif

        i915_verify_inactive(dev, __FILE__, __LINE__);

err:
        for (i = 0; i < pinned; i++)
                i915_gem_object_unpin(object_list[i]);

        for (i = 0; i < args->buffer_count; i++) {
                if (object_list[i]) {
                        obj_priv = object_list[i]->driver_private;
                        obj_priv->in_execbuffer = false;
                }
                drm_gem_object_unreference(object_list[i]);
        }

        mutex_unlock(&dev->struct_mutex);

        if (!ret) {
                /* Copy the new buffer offsets back to the user's exec list. */
                ret = copy_to_user((struct drm_i915_relocation_entry __user *)
                                   (uintptr_t) args->buffers_ptr,
                                   exec_list,
                                   sizeof(*exec_list) * args->buffer_count);
                if (ret) {
                        ret = -EFAULT;
                        DRM_ERROR("failed to copy %d exec entries "
                                  "back to user (%d)\n",
                                  args->buffer_count, ret);
                }
        }

        /* Copy the updated relocations out regardless of current error
         * state.  Failure to update the relocs would mean that the next
         * time userland calls execbuf, it would do so with presumed offset
         * state that didn't match the actual object state.
         */
        ret2 = i915_gem_put_relocs_to_user(exec_list, args->buffer_count,
                                           relocs);
        if (ret2 != 0) {
                DRM_ERROR("Failed to copy relocations back out: %d\n", ret2);

                if (ret == 0)
                        ret = ret2;
        }

pre_mutex_err:
        drm_free_large(object_list);
        drm_free_large(exec_list);
        kfree(cliprects);

        return ret;
}

int
i915_gem_object_pin(struct drm_gem_object *obj, uint32_t alignment)
{
        struct drm_device *dev = obj->dev;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        int ret;

        i915_verify_inactive(dev, __FILE__, __LINE__);
        if (obj_priv->gtt_space == NULL) {
                ret = i915_gem_object_bind_to_gtt(obj, alignment);
                if (ret != 0) {
                        if (ret != -EBUSY && ret != -ERESTARTSYS)
                                DRM_ERROR("Failure to bind: %d\n", ret);
                        return ret;
                }
        }
        /*
         * Pre-965 chips need a fence register set up in order to
         * properly handle tiled surfaces.
         */
        if (!IS_I965G(dev) && obj_priv->tiling_mode != I915_TILING_NONE) {
                ret = i915_gem_object_get_fence_reg(obj);
                if (ret != 0) {
                        if (ret != -EBUSY && ret != -ERESTARTSYS)
                                DRM_ERROR("Failure to install fence: %d\n",
                                          ret);
                        return ret;
                }
        }
        obj_priv->pin_count++;

        /* If the object is not active and not pending a flush,
         * remove it from the inactive list
         */
        if (obj_priv->pin_count == 1) {
                atomic_inc(&dev->pin_count);
                atomic_add(obj->size, &dev->pin_memory);
                if (!obj_priv->active &&
                    (obj->write_domain & I915_GEM_GPU_DOMAINS) == 0 &&
                    !list_empty(&obj_priv->list))
                        list_del_init(&obj_priv->list);
        }
        i915_verify_inactive(dev, __FILE__, __LINE__);

        return 0;
}

void
i915_gem_object_unpin(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;

        i915_verify_inactive(dev, __FILE__, __LINE__);
        obj_priv->pin_count--;
        BUG_ON(obj_priv->pin_count < 0);
        BUG_ON(obj_priv->gtt_space == NULL);

        /* If the object is no longer pinned, and is
         * neither active nor being flushed, then stick it on
         * the inactive list
         */
        if (obj_priv->pin_count == 0) {
                if (!obj_priv->active &&
                    (obj->write_domain & I915_GEM_GPU_DOMAINS) == 0)
                        list_move_tail(&obj_priv->list,
                                       &dev_priv->mm.inactive_list);
                atomic_dec(&dev->pin_count);
                atomic_sub(obj->size, &dev->pin_memory);
        }
        i915_verify_inactive(dev, __FILE__, __LINE__);
}

int
i915_gem_pin_ioctl(struct drm_device *dev, void *data,
                   struct drm_file *file_priv)
{
        struct drm_i915_gem_pin *args = data;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;
        int ret;

        mutex_lock(&dev->struct_mutex);

        obj = drm_gem_object_lookup(dev, file_priv, args->handle);
        if (obj == NULL) {
                DRM_ERROR("Bad handle in i915_gem_pin_ioctl(): %d\n",
                          args->handle);
                mutex_unlock(&dev->struct_mutex);
                return -EBADF;
        }
        obj_priv = obj->driver_private;

        if (obj_priv->pin_filp != NULL && obj_priv->pin_filp != file_priv) {
                DRM_ERROR("Already pinned in i915_gem_pin_ioctl(): %d\n",
                          args->handle);
                drm_gem_object_unreference(obj);
                mutex_unlock(&dev->struct_mutex);
                return -EINVAL;
        }

        obj_priv->user_pin_count++;
        obj_priv->pin_filp = file_priv;
        if (obj_priv->user_pin_count == 1) {
                ret = i915_gem_object_pin(obj, args->alignment);
                if (ret != 0) {
                        drm_gem_object_unreference(obj);
                        mutex_unlock(&dev->struct_mutex);
                        return ret;
                }
        }

        /* XXX - flush the CPU caches for pinned objects
         * as the X server doesn't manage domains yet
         */
        i915_gem_object_flush_cpu_write_domain(obj);
        args->offset = obj_priv->gtt_offset;
        drm_gem_object_unreference(obj);
        mutex_unlock(&dev->struct_mutex);

        return 0;
}

int
i915_gem_unpin_ioctl(struct drm_device *dev, void *data,
                     struct drm_file *file_priv)
{
        struct drm_i915_gem_pin *args = data;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;

        mutex_lock(&dev->struct_mutex);

        obj = drm_gem_object_lookup(dev, file_priv, args->handle);
        if (obj == NULL) {
                DRM_ERROR("Bad handle in i915_gem_unpin_ioctl(): %d\n",
                          args->handle);
                mutex_unlock(&dev->struct_mutex);
                return -EBADF;
        }

        obj_priv = obj->driver_private;
        if (obj_priv->pin_filp != file_priv) {
                DRM_ERROR("Not pinned by caller in i915_gem_pin_ioctl(): %d\n",
                          args->handle);
                drm_gem_object_unreference(obj);
                mutex_unlock(&dev->struct_mutex);
                return -EINVAL;
        }
        obj_priv->user_pin_count--;
        if (obj_priv->user_pin_count == 0) {
                obj_priv->pin_filp = NULL;
                i915_gem_object_unpin(obj);
        }

        drm_gem_object_unreference(obj);
        mutex_unlock(&dev->struct_mutex);
        return 0;
}

int
i915_gem_busy_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file_priv)
{
        struct drm_i915_gem_busy *args = data;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;

        obj = drm_gem_object_lookup(dev, file_priv, args->handle);
        if (obj == NULL) {
                DRM_ERROR("Bad handle in i915_gem_busy_ioctl(): %d\n",
                          args->handle);
                return -EBADF;
        }

        mutex_lock(&dev->struct_mutex);
        /* Update the active list for the hardware's current position.
         * Otherwise this only updates on a delayed timer or when irqs are
         * actually unmasked, and our working set ends up being larger than
         * required.
         */
        i915_gem_retire_requests(dev);

        obj_priv = obj->driver_private;
        /* Don't count being on the flushing list against the object being
         * done.  Otherwise, a buffer left on the flushing list but not getting
         * flushed (because nobody's flushing that domain) won't ever return
         * unbusy and get reused by libdrm's bo cache.  The other expected
         * consumer of this interface, OpenGL's occlusion queries, also specs
         * that the objects get unbusy "eventually" without any interference.
         */
        args->busy = obj_priv->active && obj_priv->last_rendering_seqno != 0;

        drm_gem_object_unreference(obj);
        mutex_unlock(&dev->struct_mutex);
        return 0;
}

int
i915_gem_throttle_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file_priv)
{
    return i915_gem_ring_throttle(dev, file_priv);
}

int i915_gem_init_object(struct drm_gem_object *obj)
{
        struct drm_i915_gem_object *obj_priv;

        obj_priv = kzalloc(sizeof(*obj_priv), GFP_KERNEL);
        if (obj_priv == NULL)
                return -ENOMEM;

        /*
         * We've just allocated pages from the kernel,
         * so they've just been written by the CPU with
         * zeros. They'll need to be clflushed before we
         * use them with the GPU.
         */
        obj->write_domain = I915_GEM_DOMAIN_CPU;
        obj->read_domains = I915_GEM_DOMAIN_CPU;

        obj_priv->agp_type = AGP_USER_MEMORY;

        obj->driver_private = obj_priv;
        obj_priv->obj = obj;
        obj_priv->fence_reg = I915_FENCE_REG_NONE;
        INIT_LIST_HEAD(&obj_priv->list);
        INIT_LIST_HEAD(&obj_priv->fence_list);

        return 0;
}

void i915_gem_free_object(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct drm_i915_gem_object *obj_priv = obj->driver_private;

        while (obj_priv->pin_count > 0)
                i915_gem_object_unpin(obj);

        if (obj_priv->phys_obj)
                i915_gem_detach_phys_object(dev, obj);

        i915_gem_object_unbind(obj);

        if (obj_priv->mmap_offset)
                i915_gem_free_mmap_offset(obj);

        kfree(obj_priv->page_cpu_valid);
        kfree(obj_priv->bit_17);
        kfree(obj->driver_private);
}

/** Unbinds all objects that are on the given buffer list. */
static int
i915_gem_evict_from_list(struct drm_device *dev, struct list_head *head)
{
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;
        int ret;

        while (!list_empty(head)) {
                obj_priv = list_first_entry(head,
                                            struct drm_i915_gem_object,
                                            list);
                obj = obj_priv->obj;

                if (obj_priv->pin_count != 0) {
                        DRM_ERROR("Pinned object in unbind list\n");
                        mutex_unlock(&dev->struct_mutex);
                        return -EINVAL;
                }

                ret = i915_gem_object_unbind(obj);
                if (ret != 0) {
                        DRM_ERROR("Error unbinding object in LeaveVT: %d\n",
                                  ret);
                        mutex_unlock(&dev->struct_mutex);
                        return ret;
                }
        }


        return 0;
}

int
i915_gem_idle(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        uint32_t seqno, cur_seqno, last_seqno;
        int stuck, ret;

        mutex_lock(&dev->struct_mutex);

        if (dev_priv->mm.suspended || dev_priv->ring.ring_obj == NULL) {
                mutex_unlock(&dev->struct_mutex);
                return 0;
        }

        /* Hack!  Don't let anybody do execbuf while we don't control the chip.
         * We need to replace this with a semaphore, or something.
         */
        dev_priv->mm.suspended = 1;
        del_timer(&dev_priv->hangcheck_timer);

        /* Cancel the retire work handler, wait for it to finish if running
         */
        mutex_unlock(&dev->struct_mutex);
        cancel_delayed_work_sync(&dev_priv->mm.retire_work);
        mutex_lock(&dev->struct_mutex);

        i915_kernel_lost_context(dev);

        /* Flush the GPU along with all non-CPU write domains
         */
        i915_gem_flush(dev, I915_GEM_GPU_DOMAINS, I915_GEM_GPU_DOMAINS);
        seqno = i915_add_request(dev, NULL, I915_GEM_GPU_DOMAINS);

        if (seqno == 0) {
                mutex_unlock(&dev->struct_mutex);
                return -ENOMEM;
        }

        dev_priv->mm.waiting_gem_seqno = seqno;
        last_seqno = 0;
        stuck = 0;
        for (;;) {
                cur_seqno = i915_get_gem_seqno(dev);
                if (i915_seqno_passed(cur_seqno, seqno))
                        break;
                if (last_seqno == cur_seqno) {
                        if (stuck++ > 100) {
                                DRM_ERROR("hardware wedged\n");
                                atomic_set(&dev_priv->mm.wedged, 1);
                                DRM_WAKEUP(&dev_priv->irq_queue);
                                break;
                        }
                }
                msleep(10);
                last_seqno = cur_seqno;
        }
        dev_priv->mm.waiting_gem_seqno = 0;

        i915_gem_retire_requests(dev);

        spin_lock(&dev_priv->mm.active_list_lock);
        if (!atomic_read(&dev_priv->mm.wedged)) {
                /* Active and flushing should now be empty as we've
                 * waited for a sequence higher than any pending execbuffer
                 */
                WARN_ON(!list_empty(&dev_priv->mm.active_list));
                WARN_ON(!list_empty(&dev_priv->mm.flushing_list));
                /* Request should now be empty as we've also waited
                 * for the last request in the list
                 */
                WARN_ON(!list_empty(&dev_priv->mm.request_list));
        }

        /* Empty the active and flushing lists to inactive.  If there's
         * anything left at this point, it means that we're wedged and
         * nothing good's going to happen by leaving them there.  So strip
         * the GPU domains and just stuff them onto inactive.
         */
        while (!list_empty(&dev_priv->mm.active_list)) {
                struct drm_i915_gem_object *obj_priv;

                obj_priv = list_first_entry(&dev_priv->mm.active_list,
                                            struct drm_i915_gem_object,
                                            list);
                obj_priv->obj->write_domain &= ~I915_GEM_GPU_DOMAINS;
                i915_gem_object_move_to_inactive(obj_priv->obj);
        }
        spin_unlock(&dev_priv->mm.active_list_lock);

        while (!list_empty(&dev_priv->mm.flushing_list)) {
                struct drm_i915_gem_object *obj_priv;

                obj_priv = list_first_entry(&dev_priv->mm.flushing_list,
                                            struct drm_i915_gem_object,
                                            list);
                obj_priv->obj->write_domain &= ~I915_GEM_GPU_DOMAINS;
                i915_gem_object_move_to_inactive(obj_priv->obj);
        }


        /* Move all inactive buffers out of the GTT. */
        ret = i915_gem_evict_from_list(dev, &dev_priv->mm.inactive_list);
        WARN_ON(!list_empty(&dev_priv->mm.inactive_list));
        if (ret) {
                mutex_unlock(&dev->struct_mutex);
                return ret;
        }

        i915_gem_cleanup_ringbuffer(dev);
        mutex_unlock(&dev->struct_mutex);

        return 0;
}

static int
i915_gem_init_hws(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;
        int ret;

        /* If we need a physical address for the status page, it's already
         * initialized at driver load time.
         */
        if (!I915_NEED_GFX_HWS(dev))
                return 0;

        obj = drm_gem_object_alloc(dev, 4096);
        if (obj == NULL) {
                DRM_ERROR("Failed to allocate status page\n");
                return -ENOMEM;
        }
        obj_priv = obj->driver_private;
        obj_priv->agp_type = AGP_USER_CACHED_MEMORY;

        ret = i915_gem_object_pin(obj, 4096);
        if (ret != 0) {
                drm_gem_object_unreference(obj);
                return ret;
        }

        dev_priv->status_gfx_addr = obj_priv->gtt_offset;

        dev_priv->hw_status_page = kmap(obj_priv->pages[0]);
        if (dev_priv->hw_status_page == NULL) {
                DRM_ERROR("Failed to map status page.\n");
                memset(&dev_priv->hws_map, 0, sizeof(dev_priv->hws_map));
                i915_gem_object_unpin(obj);
                drm_gem_object_unreference(obj);
                return -EINVAL;
        }
        dev_priv->hws_obj = obj;
        memset(dev_priv->hw_status_page, 0, PAGE_SIZE);
        I915_WRITE(HWS_PGA, dev_priv->status_gfx_addr);
        I915_READ(HWS_PGA); /* posting read */
        DRM_DEBUG("hws offset: 0x%08x\n", dev_priv->status_gfx_addr);

        return 0;
}

static void
i915_gem_cleanup_hws(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;

        if (dev_priv->hws_obj == NULL)
                return;

        obj = dev_priv->hws_obj;
        obj_priv = obj->driver_private;

        kunmap(obj_priv->pages[0]);
        i915_gem_object_unpin(obj);
        drm_gem_object_unreference(obj);
        dev_priv->hws_obj = NULL;

        memset(&dev_priv->hws_map, 0, sizeof(dev_priv->hws_map));
        dev_priv->hw_status_page = NULL;

        /* Write high address into HWS_PGA when disabling. */
        I915_WRITE(HWS_PGA, 0x1ffff000);
}

int
i915_gem_init_ringbuffer(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_gem_object *obj;
        struct drm_i915_gem_object *obj_priv;
        drm_i915_ring_buffer_t *ring = &dev_priv->ring;
        int ret;
        u32 head;

        ret = i915_gem_init_hws(dev);
        if (ret != 0)
                return ret;

        obj = drm_gem_object_alloc(dev, 128 * 1024);
        if (obj == NULL) {
                DRM_ERROR("Failed to allocate ringbuffer\n");
                i915_gem_cleanup_hws(dev);
                return -ENOMEM;
        }
        obj_priv = obj->driver_private;

        ret = i915_gem_object_pin(obj, 4096);
        if (ret != 0) {
                drm_gem_object_unreference(obj);
                i915_gem_cleanup_hws(dev);
                return ret;
        }

        /* Set up the kernel mapping for the ring. */
        ring->Size = obj->size;

        ring->map.offset = dev->agp->base + obj_priv->gtt_offset;
        ring->map.size = obj->size;
        ring->map.type = 0;
        ring->map.flags = 0;
        ring->map.mtrr = 0;

        drm_core_ioremap_wc(&ring->map, dev);
        if (ring->map.handle == NULL) {
                DRM_ERROR("Failed to map ringbuffer.\n");
                memset(&dev_priv->ring, 0, sizeof(dev_priv->ring));
                i915_gem_object_unpin(obj);
                drm_gem_object_unreference(obj);
                i915_gem_cleanup_hws(dev);
                return -EINVAL;
        }
        ring->ring_obj = obj;
        ring->virtual_start = ring->map.handle;

        /* Stop the ring if it's running. */
        I915_WRITE(PRB0_CTL, 0);
        I915_WRITE(PRB0_TAIL, 0);
        I915_WRITE(PRB0_HEAD, 0);

        /* Initialize the ring. */
        I915_WRITE(PRB0_START, obj_priv->gtt_offset);
        head = I915_READ(PRB0_HEAD) & HEAD_ADDR;

        /* G45 ring initialization fails to reset head to zero */
        if (head != 0) {
                DRM_ERROR("Ring head not reset to zero "
                          "ctl %08x head %08x tail %08x start %08x\n",
                          I915_READ(PRB0_CTL),
                          I915_READ(PRB0_HEAD),
                          I915_READ(PRB0_TAIL),
                          I915_READ(PRB0_START));
                I915_WRITE(PRB0_HEAD, 0);

                DRM_ERROR("Ring head forced to zero "
                          "ctl %08x head %08x tail %08x start %08x\n",
                          I915_READ(PRB0_CTL),
                          I915_READ(PRB0_HEAD),
                          I915_READ(PRB0_TAIL),
                          I915_READ(PRB0_START));
        }

        I915_WRITE(PRB0_CTL,
                   ((obj->size - 4096) & RING_NR_PAGES) |
                   RING_NO_REPORT |
                   RING_VALID);

        head = I915_READ(PRB0_HEAD) & HEAD_ADDR;

        /* If the head is still not zero, the ring is dead */
        if (head != 0) {
                DRM_ERROR("Ring initialization failed "
                          "ctl %08x head %08x tail %08x start %08x\n",
                          I915_READ(PRB0_CTL),
                          I915_READ(PRB0_HEAD),
                          I915_READ(PRB0_TAIL),
                          I915_READ(PRB0_START));
                return -EIO;
        }

        /* Update our cache of the ring state */
        if (!drm_core_check_feature(dev, DRIVER_MODESET))
                i915_kernel_lost_context(dev);
        else {
                ring->head = I915_READ(PRB0_HEAD) & HEAD_ADDR;
                ring->tail = I915_READ(PRB0_TAIL) & TAIL_ADDR;
                ring->space = ring->head - (ring->tail + 8);
                if (ring->space < 0)
                        ring->space += ring->Size;
        }

        return 0;
}

void
i915_gem_cleanup_ringbuffer(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;

        if (dev_priv->ring.ring_obj == NULL)
                return;

        drm_core_ioremapfree(&dev_priv->ring.map, dev);

        i915_gem_object_unpin(dev_priv->ring.ring_obj);
        drm_gem_object_unreference(dev_priv->ring.ring_obj);
        dev_priv->ring.ring_obj = NULL;
        memset(&dev_priv->ring, 0, sizeof(dev_priv->ring));

        i915_gem_cleanup_hws(dev);
}

int
i915_gem_entervt_ioctl(struct drm_device *dev, void *data,
                       struct drm_file *file_priv)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        int ret;

        if (drm_core_check_feature(dev, DRIVER_MODESET))
                return 0;

        if (atomic_read(&dev_priv->mm.wedged)) {
                DRM_ERROR("Reenabling wedged hardware, good luck\n");
                atomic_set(&dev_priv->mm.wedged, 0);
        }

        mutex_lock(&dev->struct_mutex);
        dev_priv->mm.suspended = 0;

        ret = i915_gem_init_ringbuffer(dev);
        if (ret != 0) {
                mutex_unlock(&dev->struct_mutex);
                return ret;
        }

        spin_lock(&dev_priv->mm.active_list_lock);
        BUG_ON(!list_empty(&dev_priv->mm.active_list));
        spin_unlock(&dev_priv->mm.active_list_lock);

        BUG_ON(!list_empty(&dev_priv->mm.flushing_list));
        BUG_ON(!list_empty(&dev_priv->mm.inactive_list));
        BUG_ON(!list_empty(&dev_priv->mm.request_list));
        mutex_unlock(&dev->struct_mutex);

        drm_irq_install(dev);

        return 0;
}

int
i915_gem_leavevt_ioctl(struct drm_device *dev, void *data,
                       struct drm_file *file_priv)
{
        int ret;

        if (drm_core_check_feature(dev, DRIVER_MODESET))
                return 0;

        ret = i915_gem_idle(dev);
        drm_irq_uninstall(dev);

        return ret;
}

void
i915_gem_lastclose(struct drm_device *dev)
{
        int ret;

        if (drm_core_check_feature(dev, DRIVER_MODESET))
                return;

        ret = i915_gem_idle(dev);
        if (ret)
                DRM_ERROR("failed to idle hardware: %d\n", ret);
}

void
i915_gem_load(struct drm_device *dev)
{
        int i;
        drm_i915_private_t *dev_priv = dev->dev_private;

        spin_lock_init(&dev_priv->mm.active_list_lock);
        INIT_LIST_HEAD(&dev_priv->mm.active_list);
        INIT_LIST_HEAD(&dev_priv->mm.flushing_list);
        INIT_LIST_HEAD(&dev_priv->mm.inactive_list);
        INIT_LIST_HEAD(&dev_priv->mm.request_list);
        INIT_LIST_HEAD(&dev_priv->mm.fence_list);
        INIT_DELAYED_WORK(&dev_priv->mm.retire_work,
                          i915_gem_retire_work_handler);
        dev_priv->mm.next_gem_seqno = 1;

        spin_lock(&shrink_list_lock);
        list_add(&dev_priv->mm.shrink_list, &shrink_list);
        spin_unlock(&shrink_list_lock);

        /* Old X drivers will take 0-2 for front, back, depth buffers */
        dev_priv->fence_reg_start = 3;

        if (IS_I965G(dev) || IS_I945G(dev) || IS_I945GM(dev) || IS_G33(dev))
                dev_priv->num_fence_regs = 16;
        else
                dev_priv->num_fence_regs = 8;

        /* Initialize fence registers to zero */
        if (IS_I965G(dev)) {
                for (i = 0; i < 16; i++)
                        I915_WRITE64(FENCE_REG_965_0 + (i * 8), 0);
        } else {
                for (i = 0; i < 8; i++)
                        I915_WRITE(FENCE_REG_830_0 + (i * 4), 0);
                if (IS_I945G(dev) || IS_I945GM(dev) || IS_G33(dev))
                        for (i = 0; i < 8; i++)
                                I915_WRITE(FENCE_REG_945_8 + (i * 4), 0);
        }

        i915_gem_detect_bit_6_swizzle(dev);
}

/*
 * Create a physically contiguous memory object for this object
 * e.g. for cursor + overlay regs
 */
int i915_gem_init_phys_object(struct drm_device *dev,
                              int id, int size)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_phys_object *phys_obj;
        int ret;

        if (dev_priv->mm.phys_objs[id - 1] || !size)
                return 0;

        phys_obj = kzalloc(sizeof(struct drm_i915_gem_phys_object), GFP_KERNEL);
        if (!phys_obj)
                return -ENOMEM;

        phys_obj->id = id;

        phys_obj->handle = drm_pci_alloc(dev, size, 0, 0xffffffff);
        if (!phys_obj->handle) {
                ret = -ENOMEM;
                goto kfree_obj;
        }
#ifdef CONFIG_X86
        set_memory_wc((unsigned long)phys_obj->handle->vaddr, phys_obj->handle->size / PAGE_SIZE);
#endif

        dev_priv->mm.phys_objs[id - 1] = phys_obj;

        return 0;
kfree_obj:
        kfree(phys_obj);
        return ret;
}

void i915_gem_free_phys_object(struct drm_device *dev, int id)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_phys_object *phys_obj;

        if (!dev_priv->mm.phys_objs[id - 1])
                return;

        phys_obj = dev_priv->mm.phys_objs[id - 1];
        if (phys_obj->cur_obj) {
                i915_gem_detach_phys_object(dev, phys_obj->cur_obj);
        }

#ifdef CONFIG_X86
        set_memory_wb((unsigned long)phys_obj->handle->vaddr, phys_obj->handle->size / PAGE_SIZE);
#endif
        drm_pci_free(dev, phys_obj->handle);
        kfree(phys_obj);
        dev_priv->mm.phys_objs[id - 1] = NULL;
}

void i915_gem_free_all_phys_object(struct drm_device *dev)
{
        int i;

        for (i = I915_GEM_PHYS_CURSOR_0; i <= I915_MAX_PHYS_OBJECT; i++)
                i915_gem_free_phys_object(dev, i);
}

void i915_gem_detach_phys_object(struct drm_device *dev,
                                 struct drm_gem_object *obj)
{
        struct drm_i915_gem_object *obj_priv;
        int i;
        int ret;
        int page_count;

        obj_priv = obj->driver_private;
        if (!obj_priv->phys_obj)
                return;

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                goto out;

        page_count = obj->size / PAGE_SIZE;

        for (i = 0; i < page_count; i++) {
                char *dst = kmap_atomic(obj_priv->pages[i], KM_USER0);
                char *src = obj_priv->phys_obj->handle->vaddr + (i * PAGE_SIZE);

                memcpy(dst, src, PAGE_SIZE);
                kunmap_atomic(dst, KM_USER0);
        }
        drm_clflush_pages(obj_priv->pages, page_count);
        drm_agp_chipset_flush(dev);

        i915_gem_object_put_pages(obj);
out:
        obj_priv->phys_obj->cur_obj = NULL;
        obj_priv->phys_obj = NULL;
}

int
i915_gem_attach_phys_object(struct drm_device *dev,
                            struct drm_gem_object *obj, int id)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv;
        int ret = 0;
        int page_count;
        int i;

        if (id > I915_MAX_PHYS_OBJECT)
                return -EINVAL;

        obj_priv = obj->driver_private;

        if (obj_priv->phys_obj) {
                if (obj_priv->phys_obj->id == id)
                        return 0;
                i915_gem_detach_phys_object(dev, obj);
        }


        /* create a new object */
        if (!dev_priv->mm.phys_objs[id - 1]) {
                ret = i915_gem_init_phys_object(dev, id,
                                                obj->size);
                if (ret) {
                        DRM_ERROR("failed to init phys object %d size: %zu\n", id, obj->size);
                        goto out;
                }
        }

        /* bind to the object */
        obj_priv->phys_obj = dev_priv->mm.phys_objs[id - 1];
        obj_priv->phys_obj->cur_obj = obj;

        ret = i915_gem_object_get_pages(obj);
        if (ret) {
                DRM_ERROR("failed to get page list\n");
                goto out;
        }

        page_count = obj->size / PAGE_SIZE;

        for (i = 0; i < page_count; i++) {
                char *src = kmap_atomic(obj_priv->pages[i], KM_USER0);
                char *dst = obj_priv->phys_obj->handle->vaddr + (i * PAGE_SIZE);

                memcpy(dst, src, PAGE_SIZE);
                kunmap_atomic(src, KM_USER0);
        }

        i915_gem_object_put_pages(obj);

        return 0;
out:
        return ret;
}

static int
i915_gem_phys_pwrite(struct drm_device *dev, struct drm_gem_object *obj,
                     struct drm_i915_gem_pwrite *args,
                     struct drm_file *file_priv)
{
        struct drm_i915_gem_object *obj_priv = obj->driver_private;
        void *obj_addr;
        int ret;
        char __user *user_data;

        user_data = (char __user *) (uintptr_t) args->data_ptr;
        obj_addr = obj_priv->phys_obj->handle->vaddr + args->offset;

        DRM_DEBUG("obj_addr %p, %lld\n", obj_addr, args->size);
        ret = copy_from_user(obj_addr, user_data, args->size);
        if (ret)
                return -EFAULT;

        drm_agp_chipset_flush(dev);
        return 0;
}

void i915_gem_release(struct drm_device * dev, struct drm_file *file_priv)
{
        struct drm_i915_file_private *i915_file_priv = file_priv->driver_priv;

        /* Clean up our request list when the client is going away, so that
         * later retire_requests won't dereference our soon-to-be-gone
         * file_priv.
         */
        mutex_lock(&dev->struct_mutex);
        while (!list_empty(&i915_file_priv->mm.request_list))
                list_del_init(i915_file_priv->mm.request_list.next);
        mutex_unlock(&dev->struct_mutex);
}

/* Immediately discard the backing storage */
static void
i915_gem_object_truncate(struct drm_gem_object *obj)
{
    struct inode *inode;

    inode = obj->filp->f_path.dentry->d_inode;

    mutex_lock(&inode->i_mutex);
    truncate_inode_pages(inode->i_mapping, 0);
    mutex_unlock(&inode->i_mutex);
}

static inline int
i915_gem_object_is_purgeable(struct drm_i915_gem_object *obj_priv)
{
        return !obj_priv->dirty;
}

static int
i915_gem_shrink(int nr_to_scan, gfp_t gfp_mask)
{
        drm_i915_private_t *dev_priv, *next_dev;
        struct drm_i915_gem_object *obj_priv, *next_obj;
        int cnt = 0;
        int would_deadlock = 1;

        /* "fast-path" to count number of available objects */
        if (nr_to_scan == 0) {
                spin_lock(&shrink_list_lock);
                list_for_each_entry(dev_priv, &shrink_list, mm.shrink_list) {
                        struct drm_device *dev = dev_priv->dev;

                        if (mutex_trylock(&dev->struct_mutex)) {
                                list_for_each_entry(obj_priv,
                                                    &dev_priv->mm.inactive_list,
                                                    list)
                                        cnt++;
                                mutex_unlock(&dev->struct_mutex);
                        }
                }
                spin_unlock(&shrink_list_lock);

                return (cnt / 100) * sysctl_vfs_cache_pressure;
        }

        spin_lock(&shrink_list_lock);

        /* first scan for clean buffers */
        list_for_each_entry_safe(dev_priv, next_dev,
                                 &shrink_list, mm.shrink_list) {
                struct drm_device *dev = dev_priv->dev;

                if (! mutex_trylock(&dev->struct_mutex))
                        continue;

                spin_unlock(&shrink_list_lock);

                i915_gem_retire_requests(dev);

                list_for_each_entry_safe(obj_priv, next_obj,
                                         &dev_priv->mm.inactive_list,
                                         list) {
                        if (i915_gem_object_is_purgeable(obj_priv)) {
                                struct drm_gem_object *obj = obj_priv->obj;
                                i915_gem_object_unbind(obj);
                                i915_gem_object_truncate(obj);

                                if (--nr_to_scan <= 0)
                                        break;
                        }
                }

                spin_lock(&shrink_list_lock);
                mutex_unlock(&dev->struct_mutex);

                if (nr_to_scan <= 0)
                        break;
        }

        /* second pass, evict/count anything still on the inactive list */
        list_for_each_entry_safe(dev_priv, next_dev,
                                 &shrink_list, mm.shrink_list) {
                struct drm_device *dev = dev_priv->dev;

                if (! mutex_trylock(&dev->struct_mutex))
                        continue;

                spin_unlock(&shrink_list_lock);

                list_for_each_entry_safe(obj_priv, next_obj,
                                         &dev_priv->mm.inactive_list,
                                         list) {
                        if (nr_to_scan > 0) {
                                struct drm_gem_object *obj = obj_priv->obj;
                                i915_gem_object_unbind(obj);
                                if (i915_gem_object_is_purgeable(obj_priv))
                                        i915_gem_object_truncate(obj);

                                nr_to_scan--;
                        } else
                                cnt++;
                }

                spin_lock(&shrink_list_lock);
                mutex_unlock(&dev->struct_mutex);

                would_deadlock = 0;
        }

        spin_unlock(&shrink_list_lock);

        if (would_deadlock)
                return -1;
        else if (cnt > 0)
                return (cnt / 100) * sysctl_vfs_cache_pressure;
        else
                return 0;
}

static struct shrinker shrinker = {
        .shrink = i915_gem_shrink,
        .seeks = DEFAULT_SEEKS,
};

__init void
i915_gem_shrinker_init(void)
{
    register_shrinker(&shrinker);
}

__exit void
i915_gem_shrinker_exit(void)
{
    unregister_shrinker(&shrinker);
}