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From: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Unwind partial VMA rebinding after failure in set-cache-level
Date: Fri, 9 Oct 2015 13:37:19 +0100	[thread overview]
Message-ID: <5617B4FF.1000502@linux.intel.com> (raw)
In-Reply-To: <20151009121943.GC7517@nuc-i3427.alporthouse.com>


On 09/10/15 13:19, Chris Wilson wrote:
> On Fri, Oct 09, 2015 at 01:11:47PM +0100, Tvrtko Ursulin wrote:
>>
>> On 09/10/15 12:51, Chris Wilson wrote:
>>> If the impossible happens and we fail to rebind a VMA in the middle of
>>> rebinding all VMA for an object we currently bail out and leave the
>>> object in an inconsistent state. Attempt to unwind the incomplete update
>>> by reverting all updated VMA back to the original cache-level, and WARN
>>> if that fails.
>>
>> Hey a BUG_ON would have been more your style! ;)
>
> Propagating error returns trumps throwing a tantrum and then as we are
> on the the error path we've already proved the impossible could happen,
> so presume it could happen again.

No no, just a BUG_ON(i915_bind_vma()) on the original call site would 
suffice since it cannot happen anyway. ;>

For the same reason it is safe to skip the current entry when reversing 
I suppose.

But it is still code to handle something which can't happen. If you want 
to stuff it under future proofing you can have my r-b, but hope someone 
who doesn't like future proofing notices. :)

Regards,

Tvrtko
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  reply	other threads:[~2015-10-09 12:37 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-09 11:51 [PATCH] drm/i915: Unwind partial VMA rebinding after failure in set-cache-level Chris Wilson
2015-10-09 12:11 ` Tvrtko Ursulin
2015-10-09 12:18   ` Chris Wilson
2015-10-09 12:19   ` Chris Wilson
2015-10-09 12:37     ` Tvrtko Ursulin [this message]
2015-10-09 13:10       ` Chris Wilson

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