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From: Denis Vlasenko <vda@ilport.com.ua>
To: Pekka J Enberg <penberg@cs.Helsinki.FI>
Cc: Arjan van de Ven <arjan@infradead.org>,
	Adrian Bunk <bunk@stusta.de>, Andrew Morton <akpm@osdl.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [-mm patch] make kcalloc() a static inline
Date: Mon, 15 Aug 2005 12:33:46 +0300	[thread overview]
Message-ID: <200508151233.46523.vda@ilport.com.ua> (raw)
In-Reply-To: <Pine.LNX.4.58.0508151126570.26955@sbz-30.cs.Helsinki.FI>

> > static inline void *kcalloc(size_t n, size_t size, unsigned int __nocast flags)
> > {
> > 	if (__builtin_constant_p(n)) {
> > 		if (n != 0 && size > INT_MAX / n)
> > 			return NULL;
> > 		return kzalloc(n * size, flags);
> > 	}
> > 	return kcalloc_helper(n, size, flags);
> > }
> > 
> > void *kcalloc_helper(size_t n, size_t size, unsigned int __nocast flags)
> > {
> > 	if (n != 0 && size > INT_MAX / n)
> > 		return NULL;
> > 	return kzalloc(n * size, flags);
> > }
> 
> That's extra complexity and code duplication. How much do we shave off 
> kernel text of allyesconfig with this?
> 
> Please note that whenever the caller does proper bounds checking, GCC can 
> optimize the security check away. Therefore, in practice, we don't spread 
> around the extra operations so much, I think.

gcc can optimize that away with non-const n?! I don't think so.
--
vda


  reply	other threads:[~2005-08-15  9:34 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-08-08 22:38 Adrian Bunk
2005-08-09  5:09 ` Pekka J Enberg
2005-08-15  8:06 ` [-mm patch] " Denis Vlasenko
2005-08-15  8:14   ` Arjan van de Ven
2005-08-15  8:20     ` Denis Vlasenko
2005-08-15  8:28       ` Pekka J Enberg
2005-08-15  9:33         ` Denis Vlasenko [this message]
2005-08-15  9:41           ` Arjan van de Ven
2005-08-15 12:17             ` Denis Vlasenko
2005-08-15 12:25               ` Arjan van de Ven
2005-08-15 13:06                 ` Pekka J Enberg
2005-08-15 13:51                   ` Alan Cox
2005-08-15 16:30                   ` Adrian Bunk

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