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Commit 1814f2e3 authored by Mike Snitzer's avatar Mike Snitzer
Browse files

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: default avatarMike Snitzer <snitzer@redhat.com>
parent 99f3c90d

drivers/md/dm-mpath.c

+20 −4
Original line number Diff line number Diff line
@@ -507,13 +507,27 @@ static bool __must_push_back(struct multipath *m) 


static bool must_push_back_rq(struct multipath *m)

{

	return (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) ||

	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_postsuspend(struct dm_target *ti) 
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);

}



/*