linux-kernel - Re: [PATCH RFC] slab: introduce knalloc/kxnalloc

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Message-ID: <4F33C7D7.1060801@kernel.dk>
Date:	Thu, 09 Feb 2012 14:19:19 +0100
From:	Jens Axboe <axboe@...nel.dk>
To:	Pekka Enberg <penberg@...nel.org>
CC:	Xi Wang <xi.wang@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	linux-kernel@...r.kernel.org, Christoph Lameter <cl@...ux.com>,
	Matt Mackall <mpm@...enic.com>,
	David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH RFC] slab: introduce knalloc/kxnalloc

On 02/09/2012 02:05 PM, Pekka Enberg wrote:
> On Thu, Feb 9, 2012 at 2:41 PM, Xi Wang <xi.wang@...il.com> wrote:
>> This patch introduces knalloc/kxnalloc wrappers that perform integer
>> overflow checks without zeroing the memory.
>>
>> knalloc(n, size, flags) is the non-zeroing version of kcalloc(),
>> which allocates n * size bytes.
>>
>> kxnalloc(xsize, n, size, flags) allocates xsize + n * size bytes.
>> It is useful to allocate a structure ending with a zero-length array,
>> which is a commonly used pattern.  For example, in posix_acl_alloc()
>> to allocate a posix_acl object one could call
>>
>>    kxnalloc(sizeof(struct posix_acl),
>>             count, sizeof(struct posix_acl_entry), flags);
>>
>> to avoid overflowing the allocation size.
>>
>> Suggested-by: Andrew Morton <akpm@...ux-foundation.org>
>> Signed-off-by: Xi Wang <xi.wang@...il.com>
> 
> Are there really enough potential users to justify adding both?

Agree, lets not overdesign. kmalloc_array() sounds good to me, fwiw.

-- 
Jens Axboe

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