From: Jacob Wen <jian.w.wen@oracle.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] block: insert a general SMP memory barrier before wake_up_bit()
Date: Thu, 13 Aug 2020 15:46:15 +0800 [thread overview]
Message-ID: <0a1d9db5-dc5f-5718-048d-861385ce2832@oracle.com> (raw)
In-Reply-To: <20200813073115.GA15436@infradead.org>
On 8/13/20 3:31 PM, Christoph Hellwig wrote:
> On Thu, Aug 13, 2020 at 10:44:38AM +0800, Jacob Wen wrote:
>> wake_up_bit() uses waitqueue_active() that needs the explicit smp_mb().
> Sounds like the barrier should go into wake_up_bit then..
wake_up_bit() doesn't know which one to chose: smp_mb__after_atomic() or
smp_mb().
>
>> Signed-off-by: Jacob Wen <jian.w.wen@oracle.com>
>> ---
>> fs/block_dev.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/fs/block_dev.c b/fs/block_dev.c
>> index 0ae656e022fd..e74980848a2a 100644
>> --- a/fs/block_dev.c
>> +++ b/fs/block_dev.c
>> @@ -1175,6 +1175,7 @@ static void bd_clear_claiming(struct block_device *whole, void *holder)
>> /* tell others that we're done */
>> BUG_ON(whole->bd_claiming != holder);
>> whole->bd_claiming = NULL;
>> + smp_mb();
>> wake_up_bit(&whole->bd_claiming, 0);
>> }
>>
>> --
>> 2.17.1
>>
> ---end quoted text---
next prev parent reply other threads:[~2020-08-13 7:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-13 2:44 [PATCH] block: insert a general SMP memory barrier before wake_up_bit() Jacob Wen
2020-08-13 3:00 ` Chaitanya Kulkarni
2020-08-13 7:31 ` Christoph Hellwig
2020-08-13 7:46 ` Jacob Wen [this message]
2020-08-13 11:40 ` peterz
2020-08-13 12:00 ` Matthew Wilcox
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