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Avoid taking waitqueue lock in dmapool

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With one trivial change (taking the lock slightly earlier on wakeup
from schedule), all uses of the waitq are under the pool lock, so we
can use the locked (or __) versions of the wait queue functions, and
avoid the extra spinlock.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Acked-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Matthew Wilcox 2007-12-03 12:09:33 -05:00
parent e87aa77374
commit 2cae367e48
1 changed files with 5 additions and 4 deletions
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9
mm/dmapool.c
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@ -275,8 +275,8 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
size_t offset;
void *retval;
restart:
spin_lock_irqsave(&pool->lock, flags);
restart:
list_for_each_entry(page, &pool->page_list, page_list) {
int i;
/* only cachable accesses here ... */
@ -299,12 +299,13 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
DECLARE_WAITQUEUE(wait, current);
__set_current_state(TASK_INTERRUPTIBLE);
add_wait_queue(&pool->waitq, &wait);
__add_wait_queue(&pool->waitq, &wait);
spin_unlock_irqrestore(&pool->lock, flags);
schedule_timeout(POOL_TIMEOUT_JIFFIES);
remove_wait_queue(&pool->waitq, &wait);
spin_lock_irqsave(&pool->lock, flags);
__remove_wait_queue(&pool->waitq, &wait);
goto restart;
}
retval = NULL;
@ -406,7 +407,7 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
page->in_use--;
set_bit(block, &page->bitmap[map]);
if (waitqueue_active(&pool->waitq))
wake_up(&pool->waitq);
wake_up_locked(&pool->waitq);
/*
* Resist a temptation to do
* if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page);