From: Al Viro <viro@ZenIV.linux.org.uk>
To: Andi Kleen <andi@firstfloor.org>
Cc: Maarten Lankhorst <m.b.lankhorst@gmail.com>,
Alex Elder <aelder@sgi.com>,
xfs-masters@oss.sgi.com,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
xfs@oss.sgi.com
Subject: Re: [PATCH v2] xfs: Silence bounds checking compiler warning
Date: Thu, 23 Jun 2011 18:55:33 +0100 [thread overview]
Message-ID: <20110623175533.GK11521@ZenIV.linux.org.uk> (raw)
In-Reply-To: <m2boxocvb5.fsf@firstfloor.org>
On Thu, Jun 23, 2011 at 10:27:26AM -0700, Andi Kleen wrote:
> Maarten Lankhorst <m.b.lankhorst@gmail.com> writes:
>
> > gcc with -Warray-bounds generates a false positive on this
> > since xfs defines the struct with u8 name[1]; to be able to
> > add a tag at the end.
>
> A better way would be to define it as name[0]. Then the compiler
> would know it's a VLA. You may need to check noone relies on
> the one byte though.
... and even better is to write in real C and have u8 name[]; in the
end of your structure. That's the standard C99 for this kind of thing
(see 6.7.2.1p2, p16). Zero-sized array is a gccism predating standard
flexible array members and since the standard syntax is accepted by
any gcc version that might be recent enough to build the kernel...
next prev parent reply other threads:[~2011-06-23 17:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4E037001.8090306__42924.0493024283$1308849791$gmane$org@gmail.com>
2011-06-23 17:27 ` [PATCH v2] xfs: Silence bounds checking compiler warning Andi Kleen
2011-06-23 17:55 ` Al Viro [this message]
2011-06-23 18:13 ` Christoph Hellwig
2011-06-24 2:15 ` Dave Chinner
2011-06-23 16:55 Maarten Lankhorst
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