path: root/mm/dmapool.c
diff options
authorRolf Eike Beer <eike-kernel@sf-tec.de>2011-01-13 15:47:24 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 17:32:48 -0800
commit84bc227d7fde049a568cd58a5610613feedc0dff (patch)
tree89957d8ef4dba3fe8d609bd90619f7bf6f15ec0f /mm/dmapool.c
parent43506fad21ca3d8dc59e768ff458f7c5e5c01086 (diff)
mm/dmapool.c: take lock only once in dma_pool_free()
dma_pool_free() scans for the page to free in the pool list holding the pool lock. Then it releases the lock basically to acquire it immediately again. Modify the code to only take the lock once. This will do some additional loops and computations with the lock held in if memory debugging is activated. If it is not activated the only new operations with this lock is one if and one substraction. Signed-off-by: Rolf Eike Beer <eike-kernel@sf-tec.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/dmapool.c')
1 files changed, 6 insertions, 8 deletions
diff --git a/mm/dmapool.c b/mm/dmapool.c
index 4df2de77e069..a2f6295b4df4 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -355,20 +355,15 @@ EXPORT_SYMBOL(dma_pool_alloc);
static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
- unsigned long flags;
struct dma_page *page;
- spin_lock_irqsave(&pool->lock, flags);
list_for_each_entry(page, &pool->page_list, page_list) {
if (dma < page->dma)
if (dma < (page->dma + pool->allocation))
- goto done;
+ return page;
- page = NULL;
- done:
- spin_unlock_irqrestore(&pool->lock, flags);
- return page;
+ return NULL;
@@ -386,8 +381,10 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
unsigned long flags;
unsigned int offset;
+ spin_lock_irqsave(&pool->lock, flags);
page = pool_find_page(pool, dma);
if (!page) {
+ spin_unlock_irqrestore(&pool->lock, flags);
if (pool->dev)
"dma_pool_free %s, %p/%lx (bad dma)\n",
@@ -401,6 +398,7 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
offset = vaddr - page->vaddr;
if ((dma - page->dma) != offset) {
+ spin_unlock_irqrestore(&pool->lock, flags);
if (pool->dev)
"dma_pool_free %s, %p (bad vaddr)/%Lx\n",
@@ -418,6 +416,7 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
chain = *(int *)(page->vaddr + chain);
+ spin_unlock_irqrestore(&pool->lock, flags);
if (pool->dev)
dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
"already free\n", pool->name,
@@ -432,7 +431,6 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
memset(vaddr, POOL_POISON_FREED, pool->size);
- spin_lock_irqsave(&pool->lock, flags);
*(int *)vaddr = page->offset;
page->offset = offset;