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dm mpath: add locking to multipath_resume and must_push_back

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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>
This commit is contained in:
Mike Snitzer 2016-07-25 21:08:51 -04:00
parent 99f3c90d0d
commit 1814f2e3fb
1 changed files with 20 additions and 4 deletions
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24
drivers/md/dm-mpath.c
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@ -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) ||
__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_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);
}
/*