Commit 387870f2 authored by Marek Szyprowski's avatar Marek Szyprowski
Browse files

mm: dmapool: use provided gfp flags for all dma_alloc_coherent() calls

dmapool always calls dma_alloc_coherent() with GFP_ATOMIC flag,
regardless the flags provided by the caller. This causes excessive
pruning of emergency memory pools without any good reason. Additionaly,
on ARM architecture any driver which is using dmapools will sooner or
later  trigger the following error:
"ERROR: 256 KiB atomic DMA coherent pool is too small!
Please increase it with coherent_pool= kernel parameter!".
Increasing the coherent pool size usually doesn't help much and only
delays such error, because all GFP_ATOMIC DMA allocations are always
served from the special, very limited memory pool.

This patch changes the dmapool code to correctly use gfp flags provided
by the dmapool caller.

Reported-by: default avatarSoeren Moch <>
Reported-by: default avatarThomas Petazzoni <>
Signed-off-by: default avatarMarek Szyprowski <>
Tested-by: default avatarAndrew Lunn <>
Tested-by: default avatarSoeren Moch <>
parent 29594404
......@@ -50,7 +50,6 @@ struct dma_pool { /* the pool */
size_t allocation;
size_t boundary;
char name[32];
wait_queue_head_t waitq;
struct list_head pools;
......@@ -62,8 +61,6 @@ struct dma_page { /* cacheable header for 'allocation' bytes */
unsigned int offset;
#define POOL_TIMEOUT_JIFFIES ((100 /* msec */ * HZ) / 1000)
static DEFINE_MUTEX(pools_lock);
static ssize_t
......@@ -172,7 +169,6 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
retval->size = size;
retval->boundary = boundary;
retval->allocation = allocation;
if (dev) {
int ret;
......@@ -227,7 +223,6 @@ static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
pool_initialise_page(pool, page);
list_add(&page->page_list, &pool->page_list);
page->in_use = 0;
page->offset = 0;
} else {
......@@ -315,30 +310,21 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
might_sleep_if(mem_flags & __GFP_WAIT);
spin_lock_irqsave(&pool->lock, flags);
list_for_each_entry(page, &pool->page_list, page_list) {
if (page->offset < pool->allocation)
goto ready;
page = pool_alloc_page(pool, GFP_ATOMIC);
if (!page) {
if (mem_flags & __GFP_WAIT) {
DECLARE_WAITQUEUE(wait, current);
__add_wait_queue(&pool->waitq, &wait);
spin_unlock_irqrestore(&pool->lock, flags);
/* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
spin_unlock_irqrestore(&pool->lock, flags);
page = pool_alloc_page(pool, mem_flags);
if (!page)
return NULL;
spin_lock_irqsave(&pool->lock, flags);
__remove_wait_queue(&pool->waitq, &wait);
goto restart;
retval = NULL;
goto done;
spin_lock_irqsave(&pool->lock, flags);
list_add(&page->page_list, &pool->page_list);
offset = page->offset;
......@@ -348,7 +334,6 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
memset(retval, POOL_POISON_ALLOCATED, pool->size);
spin_unlock_irqrestore(&pool->lock, flags);
return retval;
......@@ -435,8 +420,6 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
*(int *)vaddr = page->offset;
page->offset = offset;
if (waitqueue_active(&pool->waitq))
* Resist a temptation to do
* if (!is_page_busy(page)) pool_free_page(pool, page);
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