From 84bc227d7fde049a568cd58a5610613feedc0dff Mon Sep 17 00:00:00 2001 From: Rolf Eike Beer Date: Thu, 13 Jan 2011 15:47:24 -0800 Subject: [PATCH] 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/dmapool.c | 14 ++++++-------- 1 file 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) continue; 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) dev_err(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; #ifdef DMAPOOL_DEBUG if ((dma - page->dma) != offset) { + spin_unlock_irqrestore(&pool->lock, flags); if (pool->dev) dev_err(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); continue; } + 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); #endif - spin_lock_irqsave(&pool->lock, flags); page->in_use--; *(int *)vaddr = page->offset; page->offset = offset; -- 2.30.2