Message-ID: <ae90e931-df19-9d60-610c-57dc34494d8e@redhat.com>
Date:   Tue, 24 Jan 2023 11:04:58 -0500
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Subject: Re: [PATCH] Fix data race in mark_rt_mutex_waiters
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To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Hernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>,
        paulmck@kernel.org, Arjan van de Ven <arjan@linux.intel.com>,
        mingo@redhat.com, will@kernel.org, boqun.feng@gmail.com,
        akpm@osdl.org, tglx@linutronix.de, joel@joelfernandes.org,
        stern@rowland.harvard.edu, diogo.behrens@huawei.com,
        jonas.oberhauser@huawei.com, linux-kernel@vger.kernel.org,
        Hernan Ponce de Leon <hernanl.leon@huawei.com>,
        stable@vger.kernel.org
References: <20230120135525.25561-1-hernan.poncedeleon@huaweicloud.com>
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 <d1e28124-b7a7-ae19-87ec-b1dcd3701b61@redhat.com>
 <Y8/+2YBRD4rFySjh@hirez.programming.kicks-ass.net>
From:   Waiman Long <longman@redhat.com>
In-Reply-To: <Y8/+2YBRD4rFySjh@hirez.programming.kicks-ass.net>
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On 1/24/23 10:52, Peter Zijlstra wrote:
> On Tue, Jan 24, 2023 at 10:42:24AM -0500, Waiman Long wrote:
>
>> I would suggest to do it as suggested by PeterZ. Instead of set_bit(),
>> however, it is probably better to use atomic_long_or() like
>>
>> atomic_long_or_relaxed(RT_MUTEX_HAS_WAITERS, (atomic_long_t *)&lock->owner)
> That function doesn't exist, atomic_long_or() is implicitly relaxed for
> not returning a value.
>
You are right. atomic_long_or() doesn't have variants like some others.

Cheers,
Longman