dm mpath: add locking to multipath_resume and must_push_back
Multiple flags were being tested without locking. Protect against
non-atomic bit changes in m->flags by holding m->lock (while testing or
setting the queue_if_no_path related flags).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 7eac080..d7107d2 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -507,13 +507,27 @@
static bool must_push_back_rq(struct multipath *m)
{
- return (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) ||
- __must_push_back(m));
+ bool r;
+ unsigned long flags;
+
+ spin_lock_irqsave(&m->lock, flags);
+ r = (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) ||
+ __must_push_back(m));
+ spin_unlock_irqrestore(&m->lock, flags);
+
+ return r;
}
static bool must_push_back_bio(struct multipath *m)
{
- return __must_push_back(m);
+ bool r;
+ unsigned long flags;
+
+ spin_lock_irqsave(&m->lock, flags);
+ r = __must_push_back(m);
+ spin_unlock_irqrestore(&m->lock, flags);
+
+ return r;
}
/*
@@ -1680,12 +1694,14 @@
static void multipath_resume(struct dm_target *ti)
{
struct multipath *m = ti->private;
+ unsigned long flags;
+ spin_lock_irqsave(&m->lock, flags);
if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags))
set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
else
clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
- smp_mb__after_atomic();
+ spin_unlock_irqrestore(&m->lock, flags);
}
/*