From: Clemens Ladisch <clemens@ladisch.de>
To: Theodore Tso <tytso@MIT.EDU>
Cc: viresh kumar <viresh.linux@gmail.com>,
Borislav Petkov <petkovbb@googlemail.com>,
linux-kernel@vger.kernel.org
Subject: Re: QUERY: Inclusion of header files in kernel header files
Date: Wed, 24 Feb 2010 11:38:22 +0100 [thread overview]
Message-ID: <4B85019E.9040708@ladisch.de> (raw)
In-Reply-To: <07BBC9AE-C1A1-449F-AE5E-EB5B1C6323C2@mit.edu>
Theodore Tso wrote:
> Also, it's highly desirable that as much as possible multiple
> inclusion is fixed up at the same time you add extra #includes into
> header files. Protecting against multiple inclusion is critical,
> yes, but even with the protection against multiple inclusion, the
> header file has to get parsed a second time, and that slows down
> kernel compiles.
Multiple inclusion of a protected header does not hurt at all; gcc
detects that a header file uses #ifdef/#endif header guards and
automatically ignores any #include for that file if the symbol is
already defined.
Regards,
Clemens
next prev parent reply other threads:[~2010-02-24 10:38 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <22dbbef21002222241h711402f1me6b60ac7502cccd4@mail.gmail.com>
2010-02-23 6:43 ` QUERY: Inclusion of header files in kernel header files viresh kumar
2010-02-23 6:59 ` Borislav Petkov
2010-02-23 7:31 ` viresh kumar
2010-02-23 9:50 ` Borislav Petkov
2010-02-23 11:37 ` viresh kumar
2010-02-23 13:01 ` Borislav Petkov
2010-02-23 13:59 ` Stefan Richter
2010-02-24 4:23 ` viresh kumar
2010-02-23 15:15 ` Theodore Tso
2010-02-24 4:28 ` viresh kumar
2010-02-24 7:02 ` Theodore Tso
2010-02-24 10:38 ` Clemens Ladisch [this message]
2010-02-23 6:36 viresh kumar
-- strict thread matches above, loose matches on Subject: below --
2010-02-23 6:30 viresh kumar
2010-02-24 2:52 ` Eric Miao
2010-02-24 4:20 ` viresh kumar
2010-02-24 12:59 ` Laurent Pinchart
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