[PATCH] fix locking in queue_requests_store()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 7 insertions, 3 deletions

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 5fac138a5be1..caa8fcf5474b 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -3614,10 +3614,13 @@ static ssize_t
 queue_requests_store(struct request_queue *q, const char *page, size_t count)
 {
         struct request_list *rl = &q->rq;
+        unsigned long nr;
+        int ret = queue_var_store(&nr, page, count);
+        if (nr < BLKDEV_MIN_RQ)
+                nr = BLKDEV_MIN_RQ;
 
-        int ret = queue_var_store(&q->nr_requests, page, count);
-        if (q->nr_requests < BLKDEV_MIN_RQ)
-                q->nr_requests = BLKDEV_MIN_RQ;
+        spin_lock_irq(q->queue_lock);
+        q->nr_requests = nr;
         blk_queue_congestion_threshold(q);
 
         if (rl->count[READ] >= queue_congestion_on_threshold(q))
@@ -3643,6 +3646,7 @@ queue_requests_store(struct request_queue *q, const char *page, size_t count)
                 blk_clear_queue_full(q, WRITE);
                 wake_up(&rl->wait[WRITE]);
         }
+        spin_unlock_irq(q->queue_lock);
         return ret;
 }