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mm/dmapool.c: take lock only once in dma_pool_free()

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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>
This commit is contained in:
Rolf Eike Beer 2011-01-13 15:47:24 -08:00 committed by Linus Torvalds
parent 43506fad21
commit 84bc227d7f
1 changed files with 6 additions and 8 deletions
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14
mm/dmapool.c
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@ -355,21 +355,16 @@ EXPORT_SYMBOL(dma_pool_alloc);
static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma) static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
{ {
unsigned long flags;
struct dma_page *page; struct dma_page *page;
spin_lock_irqsave(&pool->lock, flags);
list_for_each_entry(page, &pool->page_list, page_list) { list_for_each_entry(page, &pool->page_list, page_list) {
if (dma < page->dma) if (dma < page->dma)
continue; continue;
if (dma < (page->dma + pool->allocation)) if (dma < (page->dma + pool->allocation))
goto done;
}
page = NULL;
done:
spin_unlock_irqrestore(&pool->lock, flags);
return page; return page;
} }
return NULL;
}
/** /**
* dma_pool_free - put block back into dma pool * dma_pool_free - put block back into dma pool
@ -386,8 +381,10 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
unsigned long flags; unsigned long flags;
unsigned int offset; unsigned int offset;
spin_lock_irqsave(&pool->lock, flags);
page = pool_find_page(pool, dma); page = pool_find_page(pool, dma);
if (!page) { if (!page) {
spin_unlock_irqrestore(&pool->lock, flags);
if (pool->dev) if (pool->dev)
dev_err(pool->dev, dev_err(pool->dev,
"dma_pool_free %s, %p/%lx (bad dma)\n", "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; offset = vaddr - page->vaddr;
#ifdef DMAPOOL_DEBUG #ifdef DMAPOOL_DEBUG
if ((dma - page->dma) != offset) { if ((dma - page->dma) != offset) {
spin_unlock_irqrestore(&pool->lock, flags);
if (pool->dev) if (pool->dev)
dev_err(pool->dev, dev_err(pool->dev,
"dma_pool_free %s, %p (bad vaddr)/%Lx\n", "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); chain = *(int *)(page->vaddr + chain);
continue; continue;
} }
spin_unlock_irqrestore(&pool->lock, flags);
if (pool->dev) if (pool->dev)
dev_err(pool->dev, "dma_pool_free %s, dma %Lx " dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
"already free\n", pool->name, "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); memset(vaddr, POOL_POISON_FREED, pool->size);
#endif #endif
spin_lock_irqsave(&pool->lock, flags);
page->in_use--; page->in_use--;
*(int *)vaddr = page->offset; *(int *)vaddr = page->offset;
page->offset = offset; page->offset = offset;