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>

diff --git a/mm/dmapool.c b/mm/dmapool.c
index 92e886d37e90613e79680ff7c3ed98cd5c55278a..b5ff9ce8765b9d4b375778b428c8fe557d984282 100644 (file)
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -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);