From: "Huang, Ying" <ying.huang@intel.com>
To: Arnd Bergmann <arnd@kernel.org>
Cc: linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Jens Axboe <axboe@kernel.dk>, Jian Cai <jiancai@google.com>,
Guenter Roeck <linux@roeck-us.net>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@suse.de>,
Eric Dumazet <eric.dumazet@gmail.com>,
Juergen Gross <jgross@suse.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Thomas Gleixner <tglx@linutronix.de>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Ingo Molnar <mingo@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
He Ying <heying24@huawei.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
clang-built-linux@googlegroups.com
Subject: Re: [PATCH] [v2] smp: fix smp_call_function_single_async prototype
Date: Thu, 06 May 2021 09:19:53 +0800 [thread overview]
Message-ID: <87czu4slom.fsf@yhuang6-desk1.ccr.corp.intel.com> (raw)
In-Reply-To: <20210505211300.3174456-1-arnd@kernel.org> (Arnd Bergmann's message of "Wed, 5 May 2021 23:12:42 +0200")
Arnd Bergmann <arnd@kernel.org> writes:
> From: Arnd Bergmann <arnd@arndb.de>
>
> As of commit 966a967116e6 ("smp: Avoid using two cache lines for struct
> call_single_data"), the smp code prefers 32-byte aligned call_single_data
> objects for performance reasons, but the block layer includes an instance
> of this structure in the main 'struct request' that is more senstive
> to size than to performance here, see 4ccafe032005 ("block: unalign
> call_single_data in struct request").
>
> The result is a violation of the calling conventions that clang correctly
> points out:
>
> block/blk-mq.c:630:39: warning: passing 8-byte aligned argument to 32-byte aligned parameter 2 of 'smp_call_function_single_async' may result in an unaligned pointer access [-Walign-mismatch]
> smp_call_function_single_async(cpu, &rq->csd);
Can this be silenced by
smp_call_function_single_async(cpu, (call_single_data_t *)&rq->csd);
Best Regards,
Huang, Ying
[snip]
next prev parent reply other threads:[~2021-05-06 1:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-05 21:12 [PATCH] [v2] smp: fix smp_call_function_single_async prototype Arnd Bergmann
2021-05-06 1:19 ` Huang, Ying [this message]
2021-05-06 7:54 ` Arnd Bergmann
2021-05-06 8:14 ` Huang, Ying
2021-05-06 8:30 ` Arnd Bergmann
2021-05-06 12:03 ` Huang, Ying
2021-05-06 14:30 ` Arnd Bergmann
2021-05-06 10:10 ` Peter Zijlstra
2021-05-06 13:48 ` [tip: locking/urgent] smp: Fix " tip-bot2 for Arnd Bergmann
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