From: Mikulas Patocka Date: Tue, 5 Feb 2019 10:09:00 +0000 (-0500) Subject: dm: add memory barrier before waitqueue_active X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=645efa84f6c7566ea863ed37a8b3247247f72e02;p=linux.git dm: add memory barrier before waitqueue_active Block core changes to switch bio-based IO accounting to be percpu had a side-effect of altering DM core to now rely on calling waitqueue_active (in both bio-based and request-based) to check if another task is in dm_wait_for_completion(). A memory barrier is needed before calling waitqueue_active(). DM core doesn't piggyback on a preceding memory barrier so it must explicitly use its own. For more details on why using waitqueue_active() without a preceding barrier is unsafe, please see the comment before the waitqueue_active() definition in include/linux/wait.h. Add the missing memory barrier by switching to using wq_has_sleeper(). Fixes: 6f75723190d8 ("dm: remove the pending IO accounting") Fixes: c4576aed8d85 ("dm: fix request-based dm's use of dm_wait_for_completion") Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer --- diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 4eb5f8c565355..a20531e5f3b4c 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -131,7 +131,7 @@ static void rq_end_stats(struct mapped_device *md, struct request *orig) static void rq_completed(struct mapped_device *md) { /* nudge anyone waiting on suspend queue */ - if (unlikely(waitqueue_active(&md->wait))) + if (unlikely(wq_has_sleeper(&md->wait))) wake_up(&md->wait); /* diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 2b53c3841b530..a0972a9301dec 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -699,7 +699,7 @@ static void end_io_acct(struct dm_io *io) true, duration, &io->stats_aux); /* nudge anyone waiting on suspend queue */ - if (unlikely(waitqueue_active(&md->wait))) + if (unlikely(wq_has_sleeper(&md->wait))) wake_up(&md->wait); }