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dma_alloc_coherent: clean it up

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This thing was rather stupidly coded.  Rework it all prior to making
changes.

Also, rename local variable `page': kernel readers expect something called
`page' to have type `struct page *'.

Cc: Guennadi Liakhovetski <lg@denx.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Dmitry Baryshkov <dbaryshkov@gmail.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrew Morton 2009-01-06 14:43:09 -08:00 committed by Linus Torvalds
parent 0bef3c2dc7
commit eccd83e116
1 changed files with 29 additions and 25 deletions
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54
kernel/dma-coherent.c
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@ -109,34 +109,38 @@ EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
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) {
/*
* Memory was found in the per-device arena.
*/
*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) {
/*
* 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;
}
if (!dev)
return 0;
mem = dev->dma_mem;
if (!mem)
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);