--- /dev/null
+/*
+ * Copyright (c) 2006 Oracle. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * 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.
+ *
+ */
+#include <linux/kernel.h>
+
+#include "rds.h"
+#include "rdma.h"
+#include "ib.h"
+
+
+/*
+ * This is stored as mr->r_trans_private.
+ */
+struct rds_ib_mr {
+ struct rds_ib_device *device;
+ struct rds_ib_mr_pool *pool;
+ struct ib_fmr *fmr;
+ struct list_head list;
+ unsigned int remap_count;
+
+ struct scatterlist *sg;
+ unsigned int sg_len;
+ u64 *dma;
+ int sg_dma_len;
+};
+
+/*
+ * Our own little FMR pool
+ */
+struct rds_ib_mr_pool {
+ struct mutex flush_lock; /* serialize fmr invalidate */
+ struct work_struct flush_worker; /* flush worker */
+
+ spinlock_t list_lock; /* protect variables below */
+ atomic_t item_count; /* total # of MRs */
+ atomic_t dirty_count; /* # dirty of MRs */
+ struct list_head drop_list; /* MRs that have reached their max_maps limit */
+ struct list_head free_list; /* unused MRs */
+ struct list_head clean_list; /* unused & unamapped MRs */
+ atomic_t free_pinned; /* memory pinned by free MRs */
+ unsigned long max_items;
+ unsigned long max_items_soft;
+ unsigned long max_free_pinned;
+ struct ib_fmr_attr fmr_attr;
+};
+
+static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all);
+static void rds_ib_teardown_mr(struct rds_ib_mr *ibmr);
+static void rds_ib_mr_pool_flush_worker(struct work_struct *work);
+
+static struct rds_ib_device *rds_ib_get_device(__be32 ipaddr)
+{
+ struct rds_ib_device *rds_ibdev;
+ struct rds_ib_ipaddr *i_ipaddr;
+
+ list_for_each_entry(rds_ibdev, &rds_ib_devices, list) {
+ spin_lock_irq(&rds_ibdev->spinlock);
+ list_for_each_entry(i_ipaddr, &rds_ibdev->ipaddr_list, list) {
+ if (i_ipaddr->ipaddr == ipaddr) {
+ spin_unlock_irq(&rds_ibdev->spinlock);
+ return rds_ibdev;
+ }
+ }
+ spin_unlock_irq(&rds_ibdev->spinlock);
+ }
+
+ return NULL;
+}
+
+static int rds_ib_add_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
+{
+ struct rds_ib_ipaddr *i_ipaddr;
+
+ i_ipaddr = kmalloc(sizeof *i_ipaddr, GFP_KERNEL);
+ if (!i_ipaddr)
+ return -ENOMEM;
+
+ i_ipaddr->ipaddr = ipaddr;
+
+ spin_lock_irq(&rds_ibdev->spinlock);
+ list_add_tail(&i_ipaddr->list, &rds_ibdev->ipaddr_list);
+ spin_unlock_irq(&rds_ibdev->spinlock);
+
+ return 0;
+}
+
+static void rds_ib_remove_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
+{
+ struct rds_ib_ipaddr *i_ipaddr, *next;
+
+ spin_lock_irq(&rds_ibdev->spinlock);
+ list_for_each_entry_safe(i_ipaddr, next, &rds_ibdev->ipaddr_list, list) {
+ if (i_ipaddr->ipaddr == ipaddr) {
+ list_del(&i_ipaddr->list);
+ kfree(i_ipaddr);
+ break;
+ }
+ }
+ spin_unlock_irq(&rds_ibdev->spinlock);
+}
+
+int rds_ib_update_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
+{
+ struct rds_ib_device *rds_ibdev_old;
+
+ rds_ibdev_old = rds_ib_get_device(ipaddr);
+ if (rds_ibdev_old)
+ rds_ib_remove_ipaddr(rds_ibdev_old, ipaddr);
+
+ return rds_ib_add_ipaddr(rds_ibdev, ipaddr);
+}
+
+int rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
+{
+ struct rds_ib_connection *ic = conn->c_transport_data;
+
+ /* conn was previously on the nodev_conns_list */
+ spin_lock_irq(&ib_nodev_conns_lock);
+ BUG_ON(list_empty(&ib_nodev_conns));
+ BUG_ON(list_empty(&ic->ib_node));
+ list_del(&ic->ib_node);
+ spin_unlock_irq(&ib_nodev_conns_lock);
+
+ spin_lock_irq(&rds_ibdev->spinlock);
+ list_add_tail(&ic->ib_node, &rds_ibdev->conn_list);
+ spin_unlock_irq(&rds_ibdev->spinlock);
+
+ ic->rds_ibdev = rds_ibdev;
+
+ return 0;
+}
+
+void rds_ib_remove_nodev_conns(void)
+{
+ struct rds_ib_connection *ic, *_ic;
+ LIST_HEAD(tmp_list);
+
+ /* avoid calling conn_destroy with irqs off */
+ spin_lock_irq(&ib_nodev_conns_lock);
+ list_splice(&ib_nodev_conns, &tmp_list);
+ INIT_LIST_HEAD(&ib_nodev_conns);
+ spin_unlock_irq(&ib_nodev_conns_lock);
+
+ list_for_each_entry_safe(ic, _ic, &tmp_list, ib_node) {
+ if (ic->conn->c_passive)
+ rds_conn_destroy(ic->conn->c_passive);
+ rds_conn_destroy(ic->conn);
+ }
+}
+
+void rds_ib_remove_conns(struct rds_ib_device *rds_ibdev)
+{
+ struct rds_ib_connection *ic, *_ic;
+ LIST_HEAD(tmp_list);
+
+ /* avoid calling conn_destroy with irqs off */
+ spin_lock_irq(&rds_ibdev->spinlock);
+ list_splice(&rds_ibdev->conn_list, &tmp_list);
+ INIT_LIST_HEAD(&rds_ibdev->conn_list);
+ spin_unlock_irq(&rds_ibdev->spinlock);
+
+ list_for_each_entry_safe(ic, _ic, &tmp_list, ib_node) {
+ if (ic->conn->c_passive)
+ rds_conn_destroy(ic->conn->c_passive);
+ rds_conn_destroy(ic->conn);
+ }
+}
+
+struct rds_ib_mr_pool *rds_ib_create_mr_pool(struct rds_ib_device *rds_ibdev)
+{
+ struct rds_ib_mr_pool *pool;
+
+ pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+ if (!pool)
+ return ERR_PTR(-ENOMEM);
+
+ INIT_LIST_HEAD(&pool->free_list);
+ INIT_LIST_HEAD(&pool->drop_list);
+ INIT_LIST_HEAD(&pool->clean_list);
+ mutex_init(&pool->flush_lock);
+ spin_lock_init(&pool->list_lock);
+ INIT_WORK(&pool->flush_worker, rds_ib_mr_pool_flush_worker);
+
+ pool->fmr_attr.max_pages = fmr_message_size;
+ pool->fmr_attr.max_maps = rds_ibdev->fmr_max_remaps;
+ pool->fmr_attr.page_shift = rds_ibdev->fmr_page_shift;
+ pool->max_free_pinned = rds_ibdev->max_fmrs * fmr_message_size / 4;
+
+ /* We never allow more than max_items MRs to be allocated.
+ * When we exceed more than max_items_soft, we start freeing
+ * items more aggressively.
+ * Make sure that max_items > max_items_soft > max_items / 2
+ */
+ pool->max_items_soft = rds_ibdev->max_fmrs * 3 / 4;
+ pool->max_items = rds_ibdev->max_fmrs;
+
+ return pool;
+}
+
+void rds_ib_get_mr_info(struct rds_ib_device *rds_ibdev, struct rds_info_rdma_connection *iinfo)
+{
+ struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
+
+ iinfo->rdma_mr_max = pool->max_items;
+ iinfo->rdma_mr_size = pool->fmr_attr.max_pages;
+}
+
+void rds_ib_destroy_mr_pool(struct rds_ib_mr_pool *pool)
+{
+ flush_workqueue(rds_wq);
+ rds_ib_flush_mr_pool(pool, 1);
+ BUG_ON(atomic_read(&pool->item_count));
+ BUG_ON(atomic_read(&pool->free_pinned));
+ kfree(pool);
+}
+
+static inline struct rds_ib_mr *rds_ib_reuse_fmr(struct rds_ib_mr_pool *pool)
+{
+ struct rds_ib_mr *ibmr = NULL;
+ unsigned long flags;
+
+ spin_lock_irqsave(&pool->list_lock, flags);
+ if (!list_empty(&pool->clean_list)) {
+ ibmr = list_entry(pool->clean_list.next, struct rds_ib_mr, list);
+ list_del_init(&ibmr->list);
+ }
+ spin_unlock_irqrestore(&pool->list_lock, flags);
+
+ return ibmr;
+}
+
+static struct rds_ib_mr *rds_ib_alloc_fmr(struct rds_ib_device *rds_ibdev)
+{
+ struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
+ struct rds_ib_mr *ibmr = NULL;
+ int err = 0, iter = 0;
+
+ while (1) {
+ ibmr = rds_ib_reuse_fmr(pool);
+ if (ibmr)
+ return ibmr;
+
+ /* No clean MRs - now we have the choice of either
+ * allocating a fresh MR up to the limit imposed by the
+ * driver, or flush any dirty unused MRs.
+ * We try to avoid stalling in the send path if possible,
+ * so we allocate as long as we're allowed to.
+ *
+ * We're fussy with enforcing the FMR limit, though. If the driver
+ * tells us we can't use more than N fmrs, we shouldn't start
+ * arguing with it */
+ if (atomic_inc_return(&pool->item_count) <= pool->max_items)
+ break;
+
+ atomic_dec(&pool->item_count);
+
+ if (++iter > 2) {
+ rds_ib_stats_inc(s_ib_rdma_mr_pool_depleted);
+ return ERR_PTR(-EAGAIN);
+ }
+
+ /* We do have some empty MRs. Flush them out. */
+ rds_ib_stats_inc(s_ib_rdma_mr_pool_wait);
+ rds_ib_flush_mr_pool(pool, 0);
+ }
+
+ ibmr = kzalloc(sizeof(*ibmr), GFP_KERNEL);
+ if (!ibmr) {
+ err = -ENOMEM;
+ goto out_no_cigar;
+ }
+
+ ibmr->fmr = ib_alloc_fmr(rds_ibdev->pd,
+ (IB_ACCESS_LOCAL_WRITE |
+ IB_ACCESS_REMOTE_READ |
+ IB_ACCESS_REMOTE_WRITE),
+ &pool->fmr_attr);
+ if (IS_ERR(ibmr->fmr)) {
+ err = PTR_ERR(ibmr->fmr);
+ ibmr->fmr = NULL;
+ printk(KERN_WARNING "RDS/IB: ib_alloc_fmr failed (err=%d)\n", err);
+ goto out_no_cigar;
+ }
+
+ rds_ib_stats_inc(s_ib_rdma_mr_alloc);
+ return ibmr;
+
+out_no_cigar:
+ if (ibmr) {
+ if (ibmr->fmr)
+ ib_dealloc_fmr(ibmr->fmr);
+ kfree(ibmr);
+ }
+ atomic_dec(&pool->item_count);
+ return ERR_PTR(err);
+}
+
+static int rds_ib_map_fmr(struct rds_ib_device *rds_ibdev, struct rds_ib_mr *ibmr,
+ struct scatterlist *sg, unsigned int nents)
+{
+ struct ib_device *dev = rds_ibdev->dev;
+ struct scatterlist *scat = sg;
+ u64 io_addr = 0;
+ u64 *dma_pages;
+ u32 len;
+ int page_cnt, sg_dma_len;
+ int i, j;
+ int ret;
+
+ sg_dma_len = ib_dma_map_sg(dev, sg, nents,
+ DMA_BIDIRECTIONAL);
+ if (unlikely(!sg_dma_len)) {
+ printk(KERN_WARNING "RDS/IB: dma_map_sg failed!\n");
+ return -EBUSY;
+ }
+
+ len = 0;
+ page_cnt = 0;
+
+ for (i = 0; i < sg_dma_len; ++i) {
+ unsigned int dma_len = ib_sg_dma_len(dev, &scat[i]);
+ u64 dma_addr = ib_sg_dma_address(dev, &scat[i]);
+
+ if (dma_addr & ~rds_ibdev->fmr_page_mask) {
+ if (i > 0)
+ return -EINVAL;
+ else
+ ++page_cnt;
+ }
+ if ((dma_addr + dma_len) & ~rds_ibdev->fmr_page_mask) {
+ if (i < sg_dma_len - 1)
+ return -EINVAL;
+ else
+ ++page_cnt;
+ }
+
+ len += dma_len;
+ }
+
+ page_cnt += len >> rds_ibdev->fmr_page_shift;
+ if (page_cnt > fmr_message_size)
+ return -EINVAL;
+
+ dma_pages = kmalloc(sizeof(u64) * page_cnt, GFP_ATOMIC);
+ if (!dma_pages)
+ return -ENOMEM;
+
+ page_cnt = 0;
+ for (i = 0; i < sg_dma_len; ++i) {
+ unsigned int dma_len = ib_sg_dma_len(dev, &scat[i]);
+ u64 dma_addr = ib_sg_dma_address(dev, &scat[i]);
+
+ for (j = 0; j < dma_len; j += rds_ibdev->fmr_page_size)
+ dma_pages[page_cnt++] =
+ (dma_addr & rds_ibdev->fmr_page_mask) + j;
+ }
+
+ ret = ib_map_phys_fmr(ibmr->fmr,
+ dma_pages, page_cnt, io_addr);
+ if (ret)
+ goto out;
+
+ /* Success - we successfully remapped the MR, so we can
+ * safely tear down the old mapping. */
+ rds_ib_teardown_mr(ibmr);
+
+ ibmr->sg = scat;
+ ibmr->sg_len = nents;
+ ibmr->sg_dma_len = sg_dma_len;
+ ibmr->remap_count++;
+
+ rds_ib_stats_inc(s_ib_rdma_mr_used);
+ ret = 0;
+
+out:
+ kfree(dma_pages);
+
+ return ret;
+}
+
+void rds_ib_sync_mr(void *trans_private, int direction)
+{
+ struct rds_ib_mr *ibmr = trans_private;
+ struct rds_ib_device *rds_ibdev = ibmr->device;
+
+ switch (direction) {
+ case DMA_FROM_DEVICE:
+ ib_dma_sync_sg_for_cpu(rds_ibdev->dev, ibmr->sg,
+ ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
+ break;
+ case DMA_TO_DEVICE:
+ ib_dma_sync_sg_for_device(rds_ibdev->dev, ibmr->sg,
+ ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
+ break;
+ }
+}
+
+static void __rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
+{
+ struct rds_ib_device *rds_ibdev = ibmr->device;
+
+ if (ibmr->sg_dma_len) {
+ ib_dma_unmap_sg(rds_ibdev->dev,
+ ibmr->sg, ibmr->sg_len,
+ DMA_BIDIRECTIONAL);
+ ibmr->sg_dma_len = 0;
+ }
+
+ /* Release the s/g list */
+ if (ibmr->sg_len) {
+ unsigned int i;
+
+ for (i = 0; i < ibmr->sg_len; ++i) {
+ struct page *page = sg_page(&ibmr->sg[i]);
+
+ /* FIXME we need a way to tell a r/w MR
+ * from a r/o MR */
+ set_page_dirty(page);
+ put_page(page);
+ }
+ kfree(ibmr->sg);
+
+ ibmr->sg = NULL;
+ ibmr->sg_len = 0;
+ }
+}
+
+static void rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
+{
+ unsigned int pinned = ibmr->sg_len;
+
+ __rds_ib_teardown_mr(ibmr);
+ if (pinned) {
+ struct rds_ib_device *rds_ibdev = ibmr->device;
+ struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
+
+ atomic_sub(pinned, &pool->free_pinned);
+ }
+}
+
+static inline unsigned int rds_ib_flush_goal(struct rds_ib_mr_pool *pool, int free_all)
+{
+ unsigned int item_count;
+
+ item_count = atomic_read(&pool->item_count);
+ if (free_all)
+ return item_count;
+
+ return 0;
+}
+
+/*
+ * Flush our pool of MRs.
+ * At a minimum, all currently unused MRs are unmapped.
+ * If the number of MRs allocated exceeds the limit, we also try
+ * to free as many MRs as needed to get back to this limit.
+ */
+static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all)
+{
+ struct rds_ib_mr *ibmr, *next;
+ LIST_HEAD(unmap_list);
+ LIST_HEAD(fmr_list);
+ unsigned long unpinned = 0;
+ unsigned long flags;
+ unsigned int nfreed = 0, ncleaned = 0, free_goal;
+ int ret = 0;
+
+ rds_ib_stats_inc(s_ib_rdma_mr_pool_flush);
+
+ mutex_lock(&pool->flush_lock);
+
+ spin_lock_irqsave(&pool->list_lock, flags);
+ /* Get the list of all MRs to be dropped. Ordering matters -
+ * we want to put drop_list ahead of free_list. */
+ list_splice_init(&pool->free_list, &unmap_list);
+ list_splice_init(&pool->drop_list, &unmap_list);
+ if (free_all)
+ list_splice_init(&pool->clean_list, &unmap_list);
+ spin_unlock_irqrestore(&pool->list_lock, flags);
+
+ free_goal = rds_ib_flush_goal(pool, free_all);
+
+ if (list_empty(&unmap_list))
+ goto out;
+
+ /* String all ib_mr's onto one list and hand them to ib_unmap_fmr */
+ list_for_each_entry(ibmr, &unmap_list, list)
+ list_add(&ibmr->fmr->list, &fmr_list);
+ ret = ib_unmap_fmr(&fmr_list);
+ if (ret)
+ printk(KERN_WARNING "RDS/IB: ib_unmap_fmr failed (err=%d)\n", ret);
+
+ /* Now we can destroy the DMA mapping and unpin any pages */
+ list_for_each_entry_safe(ibmr, next, &unmap_list, list) {
+ unpinned += ibmr->sg_len;
+ __rds_ib_teardown_mr(ibmr);
+ if (nfreed < free_goal || ibmr->remap_count >= pool->fmr_attr.max_maps) {
+ rds_ib_stats_inc(s_ib_rdma_mr_free);
+ list_del(&ibmr->list);
+ ib_dealloc_fmr(ibmr->fmr);
+ kfree(ibmr);
+ nfreed++;
+ }
+ ncleaned++;
+ }
+
+ spin_lock_irqsave(&pool->list_lock, flags);
+ list_splice(&unmap_list, &pool->clean_list);
+ spin_unlock_irqrestore(&pool->list_lock, flags);
+
+ atomic_sub(unpinned, &pool->free_pinned);
+ atomic_sub(ncleaned, &pool->dirty_count);
+ atomic_sub(nfreed, &pool->item_count);
+
+out:
+ mutex_unlock(&pool->flush_lock);
+ return ret;
+}
+
+static void rds_ib_mr_pool_flush_worker(struct work_struct *work)
+{
+ struct rds_ib_mr_pool *pool = container_of(work, struct rds_ib_mr_pool, flush_worker);
+
+ rds_ib_flush_mr_pool(pool, 0);
+}
+
+void rds_ib_free_mr(void *trans_private, int invalidate)
+{
+ struct rds_ib_mr *ibmr = trans_private;
+ struct rds_ib_device *rds_ibdev = ibmr->device;
+ struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
+ unsigned long flags;
+
+ rdsdebug("RDS/IB: free_mr nents %u\n", ibmr->sg_len);
+
+ /* Return it to the pool's free list */
+ spin_lock_irqsave(&pool->list_lock, flags);
+ if (ibmr->remap_count >= pool->fmr_attr.max_maps)
+ list_add(&ibmr->list, &pool->drop_list);
+ else
+ list_add(&ibmr->list, &pool->free_list);
+
+ atomic_add(ibmr->sg_len, &pool->free_pinned);
+ atomic_inc(&pool->dirty_count);
+ spin_unlock_irqrestore(&pool->list_lock, flags);
+
+ /* If we've pinned too many pages, request a flush */
+ if (atomic_read(&pool->free_pinned) >= pool->max_free_pinned
+ || atomic_read(&pool->dirty_count) >= pool->max_items / 10)
+ queue_work(rds_wq, &pool->flush_worker);
+
+ if (invalidate) {
+ if (likely(!in_interrupt())) {
+ rds_ib_flush_mr_pool(pool, 0);
+ } else {
+ /* We get here if the user created a MR marked
+ * as use_once and invalidate at the same time. */
+ queue_work(rds_wq, &pool->flush_worker);
+ }
+ }
+}
+
+void rds_ib_flush_mrs(void)
+{
+ struct rds_ib_device *rds_ibdev;
+
+ list_for_each_entry(rds_ibdev, &rds_ib_devices, list) {
+ struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
+
+ if (pool)
+ rds_ib_flush_mr_pool(pool, 0);
+ }
+}
+
+void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents,
+ struct rds_sock *rs, u32 *key_ret)
+{
+ struct rds_ib_device *rds_ibdev;
+ struct rds_ib_mr *ibmr = NULL;
+ int ret;
+
+ rds_ibdev = rds_ib_get_device(rs->rs_bound_addr);
+ if (!rds_ibdev) {
+ ret = -ENODEV;
+ goto out;
+ }
+
+ if (!rds_ibdev->mr_pool) {
+ ret = -ENODEV;
+ goto out;
+ }
+
+ ibmr = rds_ib_alloc_fmr(rds_ibdev);
+ if (IS_ERR(ibmr))
+ return ibmr;
+
+ ret = rds_ib_map_fmr(rds_ibdev, ibmr, sg, nents);
+ if (ret == 0)
+ *key_ret = ibmr->fmr->rkey;
+ else
+ printk(KERN_WARNING "RDS/IB: map_fmr failed (errno=%d)\n", ret);
+
+ ibmr->device = rds_ibdev;
+
+ out:
+ if (ret) {
+ if (ibmr)
+ rds_ib_free_mr(ibmr, 0);
+ ibmr = ERR_PTR(ret);
+ }
+ return ibmr;
+}
git://ftp.safe.ca / safe / jmp / linux-2.6 / commitdiff