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| author |   Mikulas Patocka <mpatocka@redhat.com> | 2019-02-05 05:09:00 -0500 |
|---|---|---|
| committer |   Mike Snitzer <snitzer@redhat.com> | 2019-02-06 17:24:37 -0500 |
| commit | 645efa84f6c7566ea863ed37a8b3247247f72e02 (patch) | |
| tree | 062ec799b850f8c0164b83a8538650dd17a448cf | |
| parent | Linux 5.0-rc5 (diff) | |
| download | linux-dev-645efa84f6c7566ea863ed37a8b3247247f72e02.tar.xz linux-dev-645efa84f6c7566ea863ed37a8b3247247f72e02.zip | |
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 <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
| -rw-r--r-- | drivers/md/dm-rq.c | 2 | ||||
| -rw-r--r-- | drivers/md/dm.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 4eb5f8c56535..a20531e5f3b4 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 2b53c3841b53..a0972a9301de 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); } |