sched: fix buddie group latency

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

diff --git a/kernel/dma-coherent.c b/kernel/dma-coherent.c
index 91e9695..0387074 100644 (file)
--- a/kernel/dma-coherent.c
+++ b/kernel/dma-coherent.c
@@ -92,7 +92,7 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
 
 /**
- * Try to allocate memory from the per-device coherent area.
+ * 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
@@ -100,33 +100,54 @@ EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
  * @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()
+ * 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.
+ * 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;
+       if (!dev)
+               return 0;
+       mem = dev->dma_mem;
+       if (!mem)
+               return 0;
+       if (unlikely(size > mem->size))
+               return 0;
+
+       pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
+       if (pageno >= 0) {
+               /*
+                * Memory was found in the per-device arena.
+                */
+               *dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
+               *ret = mem->virt_base + (pageno << PAGE_SHIFT);
+               memset(*ret, 0, size);
+       } else if (mem->flags & DMA_MEMORY_EXCLUSIVE) {
+               /*
+                * The per-device arena is exhausted and we are not
+                * permitted to fall back to generic memory.
+                */
+               *ret = NULL;
+       } else {
+               /*
+                * The per-device arena is exhausted and we are
+                * permitted to fall back to generic memory.
+                */
+                return 0;
        }
-       return (mem != NULL);
+       return 1;
 }
+EXPORT_SYMBOL(dma_alloc_from_coherent);
 
 /**
- * Try to free the memory allocated from per-device coherent memory pool.
+ * 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
@@ -135,7 +156,7 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
  * 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
+ * dma_release_coherent() should proceed with releasing memory from
  * generic pools.
  */
 int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
@@ -151,3 +172,4 @@ int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
        }
        return 0;
 }
+EXPORT_SYMBOL(dma_release_from_coherent);