From: Andreas Dilger <adilger@dilger.ca>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Shyam Saini <shyam.saini@amarulasolutions.com>,
kernel-hardening@lists.openwall.com,
linux-kernel@vger.kernel.org, keescook@chromium.org,
linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org,
intel-gvt-dev@lists.freedesktop.org,
intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
netdev@vger.kernel.org, linux-ext4 <linux-ext4@vger.kernel.org>,
devel@lists.orangefs.org, linux-mm@kvack.org,
linux-sctp@vger.kernel.org, bpf@vger.kernel.org,
kvm@vger.kernel.org, mayhs11saini@gmail.com,
Alexey Dobriyan <adobriyan@gmail.com>
Subject: Re: [PATCH V2] include: linux: Regularise the use of FIELD_SIZEOF macro
Date: Tue, 11 Jun 2019 15:28:00 -0600 [thread overview]
Message-ID: <315FEA4D-41B1-4C5B-89AA-7ABA93D66E0A@dilger.ca> (raw)
In-Reply-To: <20190611140907.899bebb12a3d731da24a9ad1@linux-foundation.org>
[-- Attachment #1: Type: text/plain, Size: 1792 bytes --]
On Jun 11, 2019, at 3:09 PM, Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Tue, 11 Jun 2019 15:00:10 -0600 Andreas Dilger <adilger@dilger.ca> wrote:
>
>>>> to FIELD_SIZEOF
>>>
>>> As Alexey has pointed out, C structs and unions don't have fields -
>>> they have members. So this is an opportunity to switch everything to
>>> a new member_sizeof().
>>>
>>> What do people think of that and how does this impact the patch footprint?
>>
>> I did a check, and FIELD_SIZEOF() is used about 350x, while sizeof_field()
>> is about 30x, and SIZEOF_FIELD() is only about 5x.
>
> Erk. Sorry, I should have grepped.
>
>> That said, I'm much more in favour of "sizeof_field()" or "sizeof_member()"
>> than FIELD_SIZEOF(). Not only does that better match "offsetof()", with
>> which it is closely related, but is also closer to the original "sizeof()".
>>
>> Since this is a rather trivial change, it can be split into a number of
>> patches to get approval/landing via subsystem maintainers, and there is no
>> huge urgency to remove the original macros until the users are gone. It
>> would make sense to remove SIZEOF_FIELD() and sizeof_field() quickly so
>> they don't gain more users, and the remaining FIELD_SIZEOF() users can be
>> whittled away as the patches come through the maintainer trees.
>
> In that case I'd say let's live with FIELD_SIZEOF() and remove
> sizeof_field() and SIZEOF_FIELD().
The real question is whether we want to live with a sub-standard macro for
the next 20 years rather than taking the opportunity to clean it up now?
> I'm a bit surprised that the FIELD_SIZEOF() definition ends up in
> stddef.h rather than in kernel.h where such things are normally
> defined. Why is that?
Cheers, Andreas
[-- Attachment #2: Message signed with OpenPGP --]
[-- Type: application/pgp-signature, Size: 873 bytes --]
next prev parent reply other threads:[~2019-06-11 21:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-11 19:38 [PATCH V2] include: linux: Regularise the use of FIELD_SIZEOF macro Shyam Saini
2019-06-11 20:46 ` Kees Cook
2019-06-11 21:05 ` Shyam Saini
2019-06-11 20:48 ` Andrew Morton
2019-06-11 21:00 ` Andreas Dilger
2019-06-11 21:09 ` Andrew Morton
2019-06-11 21:27 ` Shyam Saini
2019-06-11 21:28 ` Andreas Dilger [this message]
2019-06-29 14:25 ` Alexey Dobriyan
2019-06-29 16:45 ` Joe Perches
2019-07-02 16:33 ` Kees Cook
2019-06-12 0:05 ` Alexei Starovoitov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=315FEA4D-41B1-4C5B-89AA-7ABA93D66E0A@dilger.ca \
--to=adilger@dilger.ca \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=bpf@vger.kernel.org \
--cc=devel@lists.orangefs.org \
--cc=dri-devel@lists.freedesktop.org \
--cc=intel-gfx@lists.freedesktop.org \
--cc=intel-gvt-dev@lists.freedesktop.org \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=kvm@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-sctp@vger.kernel.org \
--cc=mayhs11saini@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=shyam.saini@amarulasolutions.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).