From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Arnd Bergmann <arnd@arndb.de>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Keisuke Nishimura" <keisuke.nishimura@inria.fr>,
"Kentaro Takeda" <takedakn@nttdata.co.jp>,
"Ayush Sawal" <ayush.sawal@chelsio.com>,
"Vinay Kumar Yadav" <vinay.yadav@chelsio.com>,
"Rohit Maheshwari" <rohitm@chelsio.com>,
"Julia Lawall" <Julia.Lawall@inria.fr>,
"Jani Nikula" <jani.nikula@intel.com>,
"Sudip Mukherjee" <sudipm.mukherjee@gmail.com>,
"Russell King" <linux@armlinux.org.uk>,
"Viresh Kumar" <vireshk@kernel.org>,
"Shiraz Hashim" <shiraz.linux.kernel@gmail.com>,
"Ville Syrjälä" <ville.syrjala@linux.intel.com>,
"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
"Maxime Ripard" <mripard@kernel.org>,
"Thomas Zimmermann" <tzimmermann@suse.de>,
"David Airlie" <airlied@linux.ie>,
"Daniel Vetter" <daniel@ffwll.ch>,
dri-devel <dri-devel@lists.freedesktop.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
"SoC Team" <soc@kernel.org>
Subject: Re: mainline build failure due to f1e4c916f97f ("drm/edid: add EDID block count and size helpers")
Date: Thu, 2 Jun 2022 20:21:14 +0900 [thread overview]
Message-ID: <74bed19a-713f-1a25-8142-cf32984beada@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <CAK8P3a1m80u+eVnoSJ-APihjNQ1se9=FG+E6tKBb-hRJx5FAVg@mail.gmail.com>
On 2022/06/02 16:38, Arnd Bergmann wrote:
>> But let's cc the tomoyo and chelsio people.
>
> I think both of them work because the structures are always
> embedded inside of larger structures that have at least word
> alignment. This is the thing I was looking for, and the
> __packed attribute was added in error, most likely copied
> from somewhere else.
The __packed in "struct tomoyo_shared_acl_head" is to embed next
naturally-aligned member of a larger struct into the bytes that
would have been wasted if __packed is not specified. For example,
struct tomoyo_shared_acl_head {
struct list_head list;
atomic_t users;
} __packed;
struct tomoyo_condition {
struct tomoyo_shared_acl_head head;
u32 size; /* Memory size allocated for this entry. */
(...snipped...)
};
saves 4 bytes on 64 bits build.
If the next naturally-aligned member of a larger struct is larger than
the bytes that was saved by __packed, the saved bytes will be unused.
next prev parent reply other threads:[~2022-06-02 11:21 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-27 9:07 mainline build failure due to f1e4c916f97f ("drm/edid: add EDID block count and size helpers") Sudip Mukherjee
2022-05-27 18:56 ` Linus Torvalds
2022-05-27 23:40 ` Sudip Mukherjee
2022-05-28 1:04 ` Linus Torvalds
2022-05-28 10:07 ` Sudip Mukherjee
2022-05-28 12:13 ` Sudip Mukherjee
2022-05-28 17:40 ` Linus Torvalds
2022-05-28 18:08 ` Linus Torvalds
2022-05-28 18:58 ` Arnd Bergmann
2022-05-28 20:31 ` Linus Torvalds
2022-05-28 21:08 ` Arnd Bergmann
2022-05-30 9:31 ` Jani Nikula
2022-05-30 9:33 ` Jani Nikula
2022-05-30 12:43 ` Arnd Bergmann
2022-05-30 13:10 ` Jani Nikula
2022-05-30 13:35 ` Arnd Bergmann
2022-05-30 14:08 ` Jani Nikula
2022-05-30 14:26 ` Arnd Bergmann
2022-05-31 6:26 ` Julia Lawall
2022-05-31 8:04 ` Arnd Bergmann
2022-05-31 16:41 ` Linus Torvalds
2022-06-01 22:28 ` Keisuke Nishimura
2022-06-02 1:08 ` Linus Torvalds
2022-06-02 7:38 ` Arnd Bergmann
2022-06-02 11:21 ` Tetsuo Handa [this message]
2022-06-02 12:11 ` Arnd Bergmann
2022-06-02 12:19 ` Christoph Hellwig
2022-06-06 10:51 ` Keisuke Nishimura
2022-05-30 16:56 ` Russell King (Oracle)
2022-05-30 16:54 ` Russell King (Oracle)
2022-05-30 16:53 ` Russell King (Oracle)
2022-05-28 20:32 ` Russell King (Oracle)
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