From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Subject: Re: [PATCH 1/2] drm/i915: Only slightly increment
	hangcheck score if we succesfully kick a ring
Date: Thu, 06 Jun 2013 17:41:59 +0300
Message-ID: <87fvwv2te0.fsf@gaia.fi.intel.com>
References: <1370511943-9775-1-git-send-email-chris@chris-wilson.co.uk>
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To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
Cc: Ben Widawsky <ben@bwidawsk.net>
List-Id: intel-gfx@lists.freedesktop.org

Chris Wilson <chris@chris-wilson.co.uk> writes:

> After kicking a ring, it should be free to make progress again and so
> should not be accused of being stuck until hangcheck fires once more. In
> order to catch a denial-of-service within a batch or across multiple
> batches, we still do increment the hangcheck score - just not as
> severely so that it takes multiple kicks to fail.
>
> This should address part of Ben's justified criticism of
>
> commit 05407ff889ceebe383aa5907219f86582ef96b72
> Author: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> Date:   Thu May 30 09:04:29 2013 +0300
>
>     drm/i915: detect hang using per ring hangcheck_score
>
> "There's also another corner case on the kick. If the seqno = 2
> (though not stuck), and on the 3rd hangcheck, the ring is stuck, and
> we try to kick it... we don't actually try to find out if the kick
> helped."
>
> v2: Make sure we catch DoS attempts with batches full of invalid WAITs.
>
> References: https://bugs.freedesktop.org/show_bug.cgi?id=65394
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> Cc: Ben Widawsky <ben@bwidawsk.net>

Hopefully Ben will also take a look as he saw exactly what
was coming.

Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>