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Avoid taking waitqueue lock in dmapool 

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);