From: Al Viro <viro@ZenIV.linux.org.uk>
To: H Hartley Sweeten <hartleys@visionengravers.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] block/genhd.c: fix sparse warning
Date: Thu, 16 Apr 2009 19:33:27 +0100 [thread overview]
Message-ID: <20090416183327.GC26366@ZenIV.linux.org.uk> (raw)
In-Reply-To: <BD79186B4FD85F4B8E60E381CAEE1909015F8F6D@mi8nycmail19.Mi8.com>
On Thu, Apr 16, 2009 at 02:03:39PM -0400, H Hartley Sweeten wrote:
> Maybe something like:
>
> #define container_of(ptr, type, member) ({ \
> const typeof( ((type *)0)->member ) *__m_##ptr = (ptr); \
> (type *)( (char *)__m_##ptr - offsetof(type,member) );})
>
> I don't know if that actually works. ;-)
_Think_ of it. Will do bleeding wonders if you say
container_of(f(), struct foo, bar)
won't it?
No, the real solution for that is this:
#define container_of(ptr, type, member) (type *) \
((char *)(1 ? (ptr) : ((const typeof(((type *)0)->member) *)(ptr))) \
- offsetof(type, member))
Same amount of typechecking, no local variables, no ({ }) uses.
prev parent reply other threads:[~2009-04-16 18:33 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-16 1:53 [PATCH] block/genhd.c: fix sparse warning H Hartley Sweeten
2009-04-16 4:46 ` Vegard Nossum
2009-04-16 5:42 ` Al Viro
2009-04-16 7:17 ` Vegard Nossum
2009-04-16 18:03 ` H Hartley Sweeten
2009-04-16 18:33 ` Al Viro [this message]
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