linux-kernel - Re: [PATCH] arch/powerpc/include/asm/barrier.h: redefine rmb and wmb to lwsync

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Message-ID: <65a0303b-f4cc-f20c-d66a-c5037bad6791@csgroup.eu>
Date:   Wed, 22 Feb 2023 08:28:19 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Kautuk Consul <kconsul@...ux.vnet.ibm.com>
CC:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arch/powerpc/include/asm/barrier.h: redefine rmb and wmb
 to lwsync



Le 22/02/2023 à 09:21, Kautuk Consul a écrit :
>> On Wed, Feb 22, 2023 at 07:02:34AM +0000, Christophe Leroy wrote:
>>>> +/* Redefine rmb() to lwsync. */
>>>
>>> WHat's the added value of this comment ? Isn't it obvious in the line
>>> below that rmb() is being defined to lwsync ? Please avoid useless comments.
>> Sure.
> Sorry, forgot to add that I wasn't adding this useless comment.
> Its just that checkpatch.pl complains that the memory barrier #define
> doesn't have a comment for it.
>>>

See https://docs.kernel.org/dev-tools/checkpatch.html, it says:

Checkpatch is not always right. Your judgement takes precedence over 
checkpatch messages. If your code looks better with the violations, then 
its probably best left alone.

checkpatch wants a comment for uses of memory barriers. Here I think it 
is a false positive.