From: Konstantin Khlebnikov Date: Sun, 3 Apr 2011 22:15:02 +0000 (+0200) Subject: block: fix request sorting at unplug X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=f83e826181f7f8fb152e4190d03854fc3a5dd040;p=deliverable%2Flinux.git block: fix request sorting at unplug Comparison function for list_sort() must be anticommutative, otherwise it is not sorting in ordinary meaning. But fortunately list_sort() always check ((*cmp)(priv, a, b) <= 0) it not distinguish negative and zero, so comparison function can implement only less-or-equal instead of full three-way comparison. Signed-off-by: Konstantin Khlebnikov Signed-off-by: Jens Axboe --- diff --git a/block/blk-core.c b/block/blk-core.c index 4fdf8953efbf..725091d5496d 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -2665,7 +2665,7 @@ static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b) struct request *rqa = container_of(a, struct request, queuelist); struct request *rqb = container_of(b, struct request, queuelist); - return !(rqa->q == rqb->q); + return !(rqa->q <= rqb->q); } static void flush_plug_list(struct blk_plug *plug)