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authorMikulas Patocka <mpatocka@redhat.com>2019-02-05 05:09:00 -0500
committerMike Snitzer <snitzer@redhat.com>2019-02-06 17:24:37 -0500
commit645efa84f6c7566ea863ed37a8b3247247f72e02 (patch)
tree062ec799b850f8c0164b83a8538650dd17a448cf /drivers/md/dm.c
parent8834f5600cf3c8db365e18a3d5cac2c2780c81e5 (diff)
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>
Diffstat (limited to 'drivers/md/dm.c')
-rw-r--r--drivers/md/dm.c2
1 files changed, 1 insertions, 1 deletions
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);
}