linux-kernel - Re: [PATCH] drm, i915: Fix memory leak in i915_gem_busy

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Message-ID: <CADZ9YHiuWT0qRO0PtL-5hLQYf5rkWs+vw4HCeR5smsnYzyQfhQ@mail.gmail.com>
Date:	Mon, 28 Nov 2011 10:29:53 +0600
From:	Rakib Mullick <rakib.mullick@...il.com>
To:	Chris Wilson <chris@...is-wilson.co.uk>
Cc:	Keith Packard <keithp@...thp.com>, akpm@...ux-foundation.org,
	dri-devel <dri-devel@...ts.freedesktop.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm, i915: Fix memory leak in i915_gem_busy_ioctl().

On Sat, Nov 26, 2011 at 10:53 PM, Chris Wilson <chris@...is-wilson.co.uk> wrote:
> On Sat, 26 Nov 2011 22:29:12 +0600, Rakib Mullick <rakib.mullick@...il.com> wrote:
>> Yes, no real problem with current code. I was just thinking from code
>> cleanup's pov. Is BUG_ON really needed in i915_add_request() ?
>
> No, just documentation as a reminder that the request should be
> preallocated, ideally so that we can fail gracefully without touching
> hardware and leaving it in an inconsistent state wrt to our bookkeeping.
> (This is more apparent in the overlay code which could hang the
> chip/driver if we hit a malloc error too late.)
>
> The BUG_ON has certainly outlived its usefulness.

Actually, I'm not seeing how BUG_ON could trigger (though, I've
wrongly mentioned in previous thread, if request == NULL, BUG_ON could
trigger), it's usefulness will never come into action. Other callers
of i915_add_request also makes sure that, it gets called only if
(request).

Although, kfree(NULL) is permitted, we shouldn't use it unnecessarily.
Anyway, since the issue is not a big deal and no real bug, it could be
droped.

Thanks,
Rakib
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