Re: [RFC PATCH 2/2] kernel/sched.c: VLA in middle of struct

From: Al Viro
Date: Wed May 13 2009 - 01:36:58 EST


On Wed, May 13, 2009 at 11:42:26AM +0930, Rusty Russell wrote:
> > > Anyway, since [] is C99, I thought it preferable to [0] which is a gcc
> > > extension. However, if C99 is really so braindead as to disallow this
> > > fairly standard trick, so I'm happy to go with the gcc extension.[1]
> >
> > No. There's a standard way to do that in C99; you can put a struct with
> > that thing into a union.
>
> Ah, thanks for the clue.
>
> How's this:
>
> sched: avoid flexible array member inside struct (gcc extension)
>
> struct sched_group and struct sched_domain end in 'unsigned long
> cpumask[]' which Jeff Garzik notes is not legal to place inside
> another struct. It upsets sparse and clang (LLVM's C front end).
>
> Al Viro pointed out that a union is the Right Way to do this.

Acked-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
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