linux-kernel - Re: [PATCH] Uninline kcalloc()

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Message-Id: <902BC866-59A0-4E50-8299-64D38D9E93B1@mac.com>
Date:	Mon, 24 Sep 2007 08:59:56 -0400
From:	Kyle Moffett <mrmacman_g4@....com>
To:	Valdis.Kletnieks@...edu
Cc:	Alexey Dobriyan <adobriyan@...il.com>, akpm@...l.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Uninline kcalloc()

On Sep 24, 2007, at 01:35:08, Valdis.Kletnieks@...edu wrote:
> On Sun, 23 Sep 2007 00:03:49 +0400, Alexey Dobriyan said:
>> -static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
>> -{
>> -	if (n != 0 && size > ULONG_MAX / n)
>> -		return NULL;
>> -	return __kmalloc(n * size, flags | __GFP_ZERO);
>> -}
>> +void *kcalloc(size_t n, size_t size, gfp_t flags);
>
> NAK.
>
> This busticates some pretty subtle code in mm/slab.c that uses uses  
> __builtin_return_address() for debugging - if you do this, then the  
> "calling function" gets listed as "kcalloc()" rather than the much  
> more useful "function that called kcalloc()" (which is what you  
> care about).
>
> (I remember going around and around multiple times getting those  
> stupid inlines set up right, so that feature actually did something  
> useful, otherwise kcalloc and kzalloc didn't report where they were  
> called from).

Proper fix is to give __kmalloc a "void *caller" parameter and have  
all of the various wrapper functions pass in the value of  
__builtin_return_address() appropriately.  I believe that even works  
properly for inline functions which may or may not be inlined.

Cheers,
Kyle Moffett

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