linux-kernel - Re: [RFC 2/4] CONFIG_STABLE: Switch off kmalloc(0) tests in slab allocators

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Message-ID: <p736468d3gj.fsf@bingen.suse.de>
Date:	01 Jun 2007 00:37:48 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Zach Brown <zach.brown@...cle.com>
Cc:	clameter@....com, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	akpm@...ux-foundation.org
Subject: Re: [RFC 2/4] CONFIG_STABLE: Switch off kmalloc(0) tests in slab allocators

Zach Brown <zach.brown@...cle.com> writes:

> > +#ifndef CONFIG_STABLE
> >  	/*
> >  	 * We should return 0 if size == 0 (which would result in the
> >  	 * kmalloc caller to get NULL) but we use the smallest object
> > @@ -81,6 +82,7 @@ static inline int kmalloc_index(size_t s
> >  	 * we can discover locations where we do 0 sized allocations.
> >  	 */
> >  	WARN_ON_ONCE(size == 0);
> > +#endif
> 
> > +#ifndef CONFIG_STABLE
> >  	WARN_ON_ONCE(size == 0);
> > +#endif
> 
> I wonder if there wouldn't be value in making a WARN_*() variant that
> contained the ifdef internally so we could lose these tedious
> surrounding ifdefs in call sites.  WARN_DEVELOPER_WHEN(), or something.
> I don't care what it's called.  

Networking has had NETDEBUG(codeblock) for this. Perhaps something
similar would be useful (DEVELOPMENT(codeblock)) in addition
to the special WARN/BUG_ONs

-Andi
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