diff options
| author | Mike Snitzer | 2020-08-24 14:19:55 -0400 |
|---|---|---|
| committer | Mike Snitzer | 2020-09-01 16:41:56 -0400 |
| commit | c322ee9320eaa4013ca3620b1130992916b19b31 (patch) | |
| tree | 2f7a395244b925895261a7386467a18054b3fc8c /drivers/md | |
| parent | f9e040efcc28309e5c592f7e79085a9a52e31f58 (diff) | |
dm mpath: fix racey management of PG initialization
Commit 935fcc56abc3 ("dm mpath: only flush workqueue when needed")
changed flush_multipath_work() to avoid needless workqueue
flushing (of a multipath global workqueue). But that change didn't
realize the surrounding flush_multipath_work() code should also only
run if 'pg_init_in_progress' is set.
Fix this by only doing all of flush_multipath_work()'s PG init related
work if 'pg_init_in_progress' is set.
Otherwise multipath_wait_for_pg_init_completion() will run
unconditionally but the preceeding flush_workqueue(kmpath_handlerd)
may not. This could lead to deadlock (though only if kmpath_handlerd
never runs a corresponding work to decrement 'pg_init_in_progress').
It could also be, though highly unlikely, that the kmpath_handlerd
work that does PG init completes before 'pg_init_in_progress' is set,
and then an intervening DM table reload's multipath_postsuspend()
triggers flush_multipath_work().
Fixes: 935fcc56abc3 ("dm mpath: only flush workqueue when needed")
Cc: stable@vger.kernel.org
Reported-by: Ben Marzinski <bmarzins@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-mpath.c | 22 |
1 files changed, 15 insertions, 7 deletions
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index e3283d35c7fd..de4da825ade6 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -1287,17 +1287,25 @@ static void multipath_wait_for_pg_init_completion(struct multipath *m) static void flush_multipath_work(struct multipath *m) { if (m->hw_handler_name) { - set_bit(MPATHF_PG_INIT_DISABLED, &m->flags); - smp_mb__after_atomic(); + unsigned long flags; + + if (!atomic_read(&m->pg_init_in_progress)) + goto skip; + + spin_lock_irqsave(&m->lock, flags); + if (atomic_read(&m->pg_init_in_progress) && + !test_and_set_bit(MPATHF_PG_INIT_DISABLED, &m->flags)) { + spin_unlock_irqrestore(&m->lock, flags); - if (atomic_read(&m->pg_init_in_progress)) flush_workqueue(kmpath_handlerd); - multipath_wait_for_pg_init_completion(m); + multipath_wait_for_pg_init_completion(m); - clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags); - smp_mb__after_atomic(); + spin_lock_irqsave(&m->lock, flags); + clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags); + } + spin_unlock_irqrestore(&m->lock, flags); } - +skip: if (m->queue_mode == DM_TYPE_BIO_BASED) flush_work(&m->process_queued_bios); flush_work(&m->trigger_event); |