From: Arjan van de Ven <arjan@linux.intel.com>
To: Hernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>,
peterz@infradead.org, mingo@redhat.com, will@kernel.org,
longman@redhat.com, boqun.feng@gmail.com, akpm@osdl.org,
tglx@linutronix.de, joel@joelfernandes.org, paulmck@kernel.org,
stern@rowland.harvard.edu, diogo.behrens@huawei.com,
jonas.oberhauser@huawei.com
Cc: linux-kernel@vger.kernel.org,
Hernan Ponce de Leon <hernanl.leon@huawei.com>,
stable@vger.kernel.org
Subject: Re: [PATCH] Fix data race in mark_rt_mutex_waiters
Date: Fri, 20 Jan 2023 06:58:20 -0800 [thread overview]
Message-ID: <562c883b-b2c3-3a27-f045-97e7e3281e0b@linux.intel.com> (raw)
In-Reply-To: <20230120135525.25561-1-hernan.poncedeleon@huaweicloud.com>
On 1/20/2023 5:55 AM, Hernan Ponce de Leon wrote:
> From: Hernan Ponce de Leon <hernanl.leon@huawei.com>
>
> kernel/locking/rtmutex.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
> index 010cf4e6d0b8..7ed9472edd48 100644
> --- a/kernel/locking/rtmutex.c
> +++ b/kernel/locking/rtmutex.c
> @@ -235,7 +235,7 @@ static __always_inline void mark_rt_mutex_waiters(struct rt_mutex_base *lock)
> unsigned long owner, *p = (unsigned long *) &lock->owner;
>
> do {
> - owner = *p;
> + owner = READ_ONCE(*p);
> } while (cmpxchg_relaxed(p, owner,
I don't see how this makes any difference at all.
*p can be read a dozen times and it's fine; cmpxchg has barrier semantics for compilers afaics
next prev parent reply other threads:[~2023-01-20 14:58 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-20 13:55 Hernan Ponce de Leon
2023-01-20 14:58 ` Arjan van de Ven [this message]
2023-01-20 15:54 ` Paul E. McKenney
2023-01-22 15:24 ` Hernan Ponce de Leon
2023-01-23 16:40 ` Paul E. McKenney
2023-01-23 17:34 ` Alan Stern
2023-01-23 17:48 ` Paul E. McKenney
2023-01-23 20:02 ` Jonas Oberhauser
2023-01-24 14:57 ` Hernan Ponce de Leon
2023-01-24 15:42 ` Waiman Long
2023-01-24 15:52 ` Peter Zijlstra
2023-01-24 16:04 ` Waiman Long
2023-01-26 9:42 ` Hernan Ponce de Leon
2023-01-26 12:20 ` Peter Zijlstra
2023-01-26 14:20 ` Peter Zijlstra
2023-01-26 21:07 ` Hernan Ponce de Leon
2023-01-26 22:10 ` David Laight
2023-01-27 1:46 ` Waiman Long
2023-03-01 16:32 ` lock_torture results for different patches: Antonio Paolillo
2023-03-06 7:58 ` Hernan Ponce de Leon
2023-03-10 17:11 ` Paul E. McKenney
2023-01-24 16:12 ` [PATCH] Fix data race in mark_rt_mutex_waiters Paul E. McKenney
2023-01-20 16:23 ` Peter Zijlstra
2023-01-20 16:58 ` David Laight
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