From: Davidlohr Bueso <dave@stgolabs.net>
To: Jason Low <jason.low2@hpe.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, Waiman Long <waiman.long@hpe.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Terry Rudd <terry.rudd@hpe.com>,
Scott J Norton <scott.norton@hpe.com>,
Jason Low <jason.low2@hp.com>
Subject: Re: [PATCH] locking/mutex: Set and clear owner using WRITE_ONCE()
Date: Thu, 19 May 2016 18:19:17 -0700 [thread overview]
Message-ID: <20160520011917.GB31084@linux-uzut.site> (raw)
In-Reply-To: <1463696630.2587.95.camel@j-VirtualBox>
On Thu, 19 May 2016, Jason Low wrote:
>The mutex owner can get read and written to without the wait_lock.
>Use WRITE_ONCE when setting and clearing the owner field in order
>to avoid optimizations such as store tearing. This avoids
>situations where the owner field gets written to with multiple
>stores and another thread could concurrently read and use a
>partially written owner value.
Right, I also ran into this with rtmutexes when avoiding the schedule()
and the spin on owner thingie.
>Signed-off-by: Jason Low <jason.low2@hpe.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
next prev parent reply other threads:[~2016-05-20 1:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-19 22:23 [PATCH] locking/mutex: Set and clear owner using WRITE_ONCE() Jason Low
2016-05-20 1:19 ` Davidlohr Bueso [this message]
2016-05-20 20:27 ` Waiman Long
2016-05-20 22:09 ` Jason Low
2016-05-21 1:00 ` Davidlohr Bueso
2016-05-21 4:09 ` Waiman Long
2016-05-23 20:40 ` Jason Low
2016-05-23 21:31 ` Davidlohr Bueso
2016-05-23 21:49 ` Jason Low
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