From: Al Viro <viro@zeniv.linux.org.uk>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Yury Norov <yury.norov@gmail.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>
Subject: Re: [PATCH v1 1/1] kernel.h: Drop inclusion in bitmap.h
Date: Sat, 27 Mar 2021 22:18:04 +0000 [thread overview]
Message-ID: <YF+vHHxYQ1hnnNBm@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <20210326170347.37441-1-andriy.shevchenko@linux.intel.com>
On Fri, Mar 26, 2021 at 07:03:47PM +0200, Andy Shevchenko wrote:
> The bitmap.h header is used in a lot of code around the kernel.
> Besides that it includes kernel.h which sometimes makes a loop.
How much of the kernel does *not* end up pulling kernel.h anyway,
making all subsequent includes fast no-ops?
Realistically, any C compiler is going to recognize the case when
included file has contents of form
#ifndef <pp-id>
#define <pp-id> <possibly empty sequence of preprocessor tokens>
<lines>
#endif
where <lines> contain no exposed #else, #elif or #endif and
remember that subsequent includes of that file should be ignored
unless <pp-id> becomes undefined.
AFAICS, on e.g. allmodconfig amd64 build it's (at most - there
might've been false positives) 131 files out of ~30000; on
defconfig it's 55 out of ~2300. How much does your patch
change that?
next prev parent reply other threads:[~2021-03-27 22:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 17:03 [PATCH v1 1/1] kernel.h: Drop inclusion in bitmap.h Andy Shevchenko
2021-03-27 21:32 ` Yury Norov
2021-03-27 22:18 ` Al Viro [this message]
2021-03-27 22:38 ` Andy Shevchenko
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=YF+vHHxYQ1hnnNBm@zeniv-ca.linux.org.uk \
--to=viro@zeniv.linux.org.uk \
--cc=akpm@linux-foundation.org \
--cc=andriy.shevchenko@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@rasmusvillemoes.dk \
--cc=yury.norov@gmail.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.