linux-kernel - Re: [PATCH v2 2/2] fscache: Add the missing smp_mb__after_atomic() before wake_up

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Date:   Wed, 11 Jan 2023 16:24:59 +0000
From:   David Howells <dhowells@...hat.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     dhowells@...hat.com, Hou Tao <houtao@...weicloud.com>,
        linux-cachefs@...hat.com, Jeff Layton <jlayton@...nel.org>,
        linux-erofs@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Jingbo Xu <jefflexu@...ux.alibaba.com>, houtao1@...wei.com
Subject: Re: [PATCH v2 2/2] fscache: Add the missing smp_mb__after_atomic() before wake_up_bit()

David Howells <dhowells@...hat.com> wrote:

> What two values are you ordering?
> 
> If we're using this to create a critical section, then yes, we would need a
> barrier to order the changes inside the critical section before changing the
> memory location that forms the lock - but this is not a critical section.

Actually, that said, the ordering is probably between the bit being cleared
and the task state.

David