Re: [PATCH] drm/i915: Use kcalloc more

Daniel Vetter
2013-09-19T12:35:42Z

On Thu, Sep 19, 2013 at 2:30 PM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> On Thu, Sep 19, 2013 at 02:06:39PM +0200, Daniel Vetter wrote:
>> No buffer overflows here, but better safe than sorry.
>>
>> v2:
>> - Fixup the sizeof conversion, I've missed the pointer deref (Jani).
>> - Drop the redundant GFP_ZERO, kcalloc alreads memsets (Jani).
>> - Use kmalloc_array for the execbuf fastpath to avoid the memset
>> (Chris). I've opted to leave all other conversions as-is since they
>> aren't in a fastpath and dealing with cleared memory instead of
>> random garbage is just generally nicer.
>
> I still don't agree with this change to kmalloc_array. The code is
> written explicitly such that an invalid buffer_count is reported as
> EINVAL and not ENOMEM.

It's just paranoia - imo consistently using kcalloc/kmalloc array
where possible is just safer. Note also that the subtest I've added
explicitly checks for EINVAL, so if we ever botch this it should get
caught.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch