From: Andrea Parri <andrea.parri@amarulasolutions.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
Omar Sandoval <osandov@fb.com>,
linux-block@vger.kernel.org
Subject: Re: [PATCH 3/5] sbitmap: fix improper use of smp_mb__before_atomic()
Date: Fri, 10 May 2019 08:27:27 +0200 [thread overview]
Message-ID: <20190510062727.GA4607@andrea> (raw)
In-Reply-To: <20190510034101.GC27944@ming.t460p>
Hi Ming,
On Fri, May 10, 2019 at 11:41:02AM +0800, Ming Lei wrote:
> On Mon, Apr 29, 2019 at 10:14:59PM +0200, Andrea Parri wrote:
> > This barrier only applies to the read-modify-write operations; in
> > particular, it does not apply to the atomic_set() primitive.
> >
> > Replace the barrier with an smp_mb().
> >
> > Fixes: 6c0ca7ae292ad ("sbitmap: fix wakeup hang after sbq resize")
> > Cc: stable@vger.kernel.org
> > Reported-by: "Paul E. McKenney" <paulmck@linux.ibm.com>
> > Reported-by: Peter Zijlstra <peterz@infradead.org>
> > Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
> > Cc: Jens Axboe <axboe@kernel.dk>
> > Cc: Omar Sandoval <osandov@fb.com>
> > Cc: linux-block@vger.kernel.org
> > ---
> > lib/sbitmap.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/lib/sbitmap.c b/lib/sbitmap.c
> > index 155fe38756ecf..4a7fc4915dfc6 100644
> > --- a/lib/sbitmap.c
> > +++ b/lib/sbitmap.c
> > @@ -435,7 +435,7 @@ static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,
> > * to ensure that the batch size is updated before the wait
> > * counts.
> > */
> > - smp_mb__before_atomic();
> > + smp_mb();
> > for (i = 0; i < SBQ_WAIT_QUEUES; i++)
> > atomic_set(&sbq->ws[i].wait_cnt, 1);
> > }
> > --
> > 2.7.4
> >
>
> sbitmap_queue_update_wake_batch() won't be called in fast path, and
> the fix is correct too, so:
>
> Reviewed-by: Ming Lei <ming.lei@redhat.com>
Thank you for the review(s),
Andrea
> thanks,
> Ming
prev parent reply other threads:[~2019-05-10 6:29 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1556568902-12464-1-git-send-email-andrea.parri@amarulasolutions.com>
2019-04-29 20:14 ` [PATCH 2/5] bio: fix improper use of smp_mb__before_atomic() Andrea Parri
2019-04-30 8:21 ` Peter Zijlstra
2019-05-09 20:23 ` Andrea Parri
2019-05-10 3:40 ` Ming Lei
2019-04-29 20:14 ` [PATCH 3/5] sbitmap: " Andrea Parri
2019-05-09 20:26 ` Andrea Parri
2019-05-10 3:41 ` Ming Lei
2019-05-10 6:27 ` Andrea Parri [this message]
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