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Date: Fri, 10 Feb 2012 15:58:25 +0200
Message-ID: <CACVxJT92s+XptSm+aNcbhNi0ovEwT0PSSCTiq=VYsbKDRKQWdw@mail.gmail.com>
Subject: Re: [PATCH RFC v2] slab: introduce kmalloc_array
From: Alexey Dobriyan <adobriyan@gmail.com>
To: Xi Wang <xi.wang@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>, Pekka Enberg <penberg@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dan Carpenter <dan.carpenter@oracle.com>, linux-kernel@vger.kernel.org,
        Christoph Lameter <cl@linux.com>, Matt Mackall <mpm@selenic.com>,
        David Rientjes <rientjes@google.com>
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On Fri, Feb 10, 2012 at 4:55 PM, Xi Wang <xi.wang@gmail.com> wrote:
> On Feb 10, 2012, at 8:11 AM, Alexey Dobriyan wrote:

>> Also, it could be written more "robust" against people who will make
>> sizeof() the first argument with __builtin_constant_p().

No,

If one dimension is constant, limit should be divided by it, so
compiler would have less chance
to screw up compile time evaluation.

Also, gfp_t mask could be made first argument if we ever want to
expand it to >2 dimensional arrays
without adding kaalloc3().

> Do you mean something like this?
>
>  BUILD_BUG_ON(__builtin_constant_p(n));
>
> or
>
>  BUILD_BUG_ON(__builtin_constant_p(n) && !__builtin_constant_p(size));
>
> - xi
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