drm/i915: Check for dev->primary->master before dereference.

[safe/jmp/linux-2.6] / kernel / dma-coherent.c

diff --git a/kernel/dma-coherent.c b/kernel/dma-coherent.c
index 56dff5c..962a3b5 100644 (file)
--- a/kernel/dma-coherent.c
+++ b/kernel/dma-coherent.c
@@ -77,40 +77,89 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
 {
        struct dma_coherent_mem *mem = dev->dma_mem;
        int pos, err;
-       int pages = (size + (device_addr & ~PAGE_MASK) + PAGE_SIZE - 1);
 
-       pages >>= PAGE_SHIFT;
+       size += device_addr & ~PAGE_MASK;
 
        if (!mem)
                return ERR_PTR(-EINVAL);
 
        pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
-       err = bitmap_allocate_region(mem->bitmap, pos, get_order(pages));
+       err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
        if (err != 0)
                return ERR_PTR(err);
        return mem->virt_base + (pos << PAGE_SHIFT);
 }
 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
 
+/**
+ * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area
+ *
+ * @dev:       device from which we allocate memory
+ * @size:      size of requested memory area
+ * @dma_handle:        This will be filled with the correct dma handle
+ * @ret:       This pointer will be filled with the virtual address
+ *             to allocated area.
+ *
+ * This function should be only called from per-arch dma_alloc_coherent()
+ * to support allocation from per-device coherent memory pools.
+ *
+ * Returns 0 if dma_alloc_coherent should continue with allocating from
+ * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
+ */
 int dma_alloc_from_coherent(struct device *dev, ssize_t size,
                                       dma_addr_t *dma_handle, void **ret)
 {
-       struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
+       struct dma_coherent_mem *mem;
        int order = get_order(size);
+       int pageno;
 
-       if (mem) {
-               int page = bitmap_find_free_region(mem->bitmap, mem->size,
-                                                    order);
-               if (page >= 0) {
-                       *dma_handle = mem->device_base + (page << PAGE_SHIFT);
-                       *ret = mem->virt_base + (page << PAGE_SHIFT);
-                       memset(*ret, 0, size);
-               } else if (mem->flags & DMA_MEMORY_EXCLUSIVE)
-                       *ret = NULL;
-       }
-       return (mem != NULL);
-}
+       if (!dev)
+               return 0;
+       mem = dev->dma_mem;
+       if (!mem)
+               return 0;
+
+       *ret = NULL;
 
+       if (unlikely(size > (mem->size << PAGE_SHIFT)))
+               goto err;
+
+       pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
+       if (unlikely(pageno < 0))
+               goto err;
+
+       /*
+        * Memory was found in the per-device area.
+        */
+       *dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
+       *ret = mem->virt_base + (pageno << PAGE_SHIFT);
+       memset(*ret, 0, size);
+
+       return 1;
+
+err:
+       /*
+        * In the case where the allocation can not be satisfied from the
+        * per-device area, try to fall back to generic memory if the
+        * constraints allow it.
+        */
+       return mem->flags & DMA_MEMORY_EXCLUSIVE;
+}
+EXPORT_SYMBOL(dma_alloc_from_coherent);
+
+/**
+ * dma_release_from_coherent() - try to free the memory allocated from per-device coherent memory pool
+ * @dev:       device from which the memory was allocated
+ * @order:     the order of pages allocated
+ * @vaddr:     virtual address of allocated pages
+ *
+ * This checks whether the memory was allocated from the per-device
+ * coherent memory pool and if so, releases that memory.
+ *
+ * Returns 1 if we correctly released the memory, or 0 if
+ * dma_release_coherent() should proceed with releasing memory from
+ * generic pools.
+ */
 int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
 {
        struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
@@ -124,3 +173,4 @@ int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
        }
        return 0;
 }
+EXPORT_SYMBOL(dma_release_from_coherent);