From: David Laight <David.Laight@ACULAB.COM>
To: 'Nathan Chancellor' <nathan@kernel.org>, Jian Cai <jiancai@google.com>
Cc: "cjdb@google.com" <cjdb@google.com>,
"manojgupta@google.com" <manojgupta@google.com>,
"llozano@google.com" <llozano@google.com>,
"clang-built-linux@googlegroups.com"
<clang-built-linux@googlegroups.com>,
Guenter Roeck <linux@roeck-us.net>, Jens Axboe <axboe@kernel.dk>,
"Nick Desaulniers" <ndesaulniers@google.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] blk-mq: fix alignment mismatch.
Date: Wed, 31 Mar 2021 10:38:15 +0000 [thread overview]
Message-ID: <553e40c54eea408a96f42eec53616993@AcuMS.aculab.com> (raw)
In-Reply-To: <20210330232946.m5p7426macyjduzm@archlinux-ax161>
From: Nathan Chancellor
> Sent: 31 March 2021 00:30
>
> Hi Jian,
>
> On Tue, Mar 30, 2021 at 04:02:49PM -0700, Jian Cai wrote:
> > This fixes the mismatch of alignments between csd and its use as an
> > argument to smp_call_function_single_async, which causes build failure
> > when -Walign-mismatch in Clang is used.
> >
> > Link:
> > http://crrev.com/c/1193732
> >
> > Suggested-by: Guenter Roeck <linux@roeck-us.net>
> > Signed-off-by: Jian Cai <jiancai@google.com>
>
> Thanks for the patch. This is effectively a revert of commit
> 4ccafe032005 ("block: unalign call_single_data in struct request"),
> which I had brought up in this thread:
>
> https://lore.kernel.org/r/20210310182307.zzcbi5w5jrmveld4@archlinux-ax161/
>
> This is obviously a correct fix, I am not just sure what the impact to
> 'struct request' will be.
If the structure is allocated on-stack then aligning it
requires the compiler generate the rather horrid
'double stack frame' for the function.
Possibly the unaligned 'struct' should be used by all
the code except for a few places where it makes sense
to allocate an aligned item?
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
prev parent reply other threads:[~2021-03-31 10:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-30 23:02 [PATCH] blk-mq: fix alignment mismatch Jian Cai
2021-03-30 23:12 ` Guenter Roeck
2021-03-30 23:29 ` Nathan Chancellor
2021-03-31 0:26 ` Guenter Roeck
2021-03-31 1:31 ` Jian Cai
2021-03-31 21:27 ` Jian Cai
2021-03-31 21:58 ` Nathan Chancellor
2021-03-31 22:06 ` Nick Desaulniers
2021-04-08 17:57 ` Jian Cai
2021-04-08 18:12 ` Nathan Chancellor
2021-04-08 18:42 ` Jian Cai
2021-04-08 19:44 ` [PATCH] block: Disable -Walign-mismatch for blk-mq.c Nathan Chancellor
2021-04-08 19:52 ` Guenter Roeck
2021-03-31 10:38 ` David Laight [this message]
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