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From: Chris Wilson <chris@chris-wilson.co.uk>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Intel Graphics Development <intel-gfx@lists.freedesktop.org>
Subject: Re: [PATCH 1/2] drm/i915: clear up wedged transitions
Date: Wed, 3 Sep 2014 21:26:14 +0100
Message-ID: <20140903202614.GD3171@nuc-i3427.alporthouse.com> (raw)
In-Reply-To: <1352996243-15590-1-git-send-email-daniel.vetter@ffwll.ch>

On Thu, Nov 15, 2012 at 05:17:22PM +0100, Daniel Vetter wrote:
> We have two important transitions of the wedged state in the current
> code:
> 
> - 0 -> 1: This means a hang has been detected, and signals to everyone
>   that they please get of any locks, so that the reset work item can
>   do its job.
> 
> - 1 -> 0: The reset handler has completed.
> 
> Now the last transition mixes up two states: "Reset completed and
> successful" and "Reset failed". To distinguish these two we do some
> tricks with the reset completion, but I simply could not convince
> myself that this doesn't race under odd circumstances.
> 
> Hence split this up, and add a new terminal state indicating that the
> hw is gone for good.
> 
> Also add explicit #defines for both states, update comments.
> 
> v2: Split out the reset handling bugfix for the throttle ioctl.
> 
> v3: s/tmp/wedged/ sugested by Chris Wilson. Also fixup up a rebase
> error which prevented this patch from actually compiling.
> 
> v4: To unify the wedged state with the reset counter, keep the
> reset-in-progress state just as a flag. The terminally-wedged state is
> now denoted with a big number.
> 
> v5: Add a comment to the reset_counter special values explaining that
> WEDGED & RESET_IN_PROGRESS needs to be true for the code to be
> correct.
> 
> v6: Fixup logic errors introduced with the wedged+reset_counter
> unification. Since WEDGED implies reset-in-progress (in a way we're
> terminally stuck in the dead-but-reset-not-completed state), we need
> ensure that we check for this everywhere. The specific bug was in
> wait_for_error, which would simply have timed out.
> 
> v7: Extract an inline i915_reset_in_progress helper to make the code
> more readable. Also annote the reset-in-progress case with an
> unlikely, to help the compiler optimize the fastpath. Do the same for
> the terminally wedged case with i915_terminally_wedged.
> 
> Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> @@ -1385,7 +1372,7 @@ out:
>  		/* If this -EIO is due to a gpu hang, give the reset code a
>  		 * chance to clean up the mess. Otherwise return the proper
>  		 * SIGBUS. */
> -		if (!atomic_read(&dev_priv->gpu_error.wedged))
> +		if (i915_terminally_wedged(&dev_priv->gpu_error))
>  			return VM_FAULT_SIGBUS;

(i915_gem_fault())

This if() is backwards.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

  parent reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-11-14 16:14 [PATCH 0/6] robustify reset transitions Daniel Vetter
2012-11-14 16:14 ` [PATCH 1/6] drm/i915: move dev_priv->mm out of line Daniel Vetter
2012-12-04 16:31   ` Damien Lespiau
2012-11-14 16:14 ` [PATCH 2/6] drm/i915: extract hangcheck/reset/error_state state into substruct Daniel Vetter
2012-12-04 17:20   ` Damien Lespiau
2012-11-14 16:14 ` [PATCH 3/6] drm/i915: move wedged to the other gpu error handling stuff Daniel Vetter
2012-12-04 17:24   ` Damien Lespiau
2012-11-14 16:14 ` [PATCH 4/6] drm/i915: fix reset handling in the throttle ioctl Daniel Vetter
2012-12-05 14:08   ` Damien Lespiau
2012-11-14 16:14 ` [PATCH 5/6] drm/i915: clear up wedged transitions Daniel Vetter
2012-11-14 16:14 ` [PATCH 6/6] drm/i915: create a race-free reset detection Daniel Vetter
2012-11-15 16:17 ` [PATCH 1/2] drm/i915: clear up wedged transitions Daniel Vetter
2012-11-15 16:17   ` [PATCH 2/2] drm/i915: create a race-free reset detection Daniel Vetter
2012-12-05 16:35     ` Damien Lespiau
2012-12-06  8:01       ` [PATCH] " Daniel Vetter
2012-12-06 15:23       ` [PATCH] drm/i915: clarify concurrent hang detect/gpu reset consistency Daniel Vetter
2013-01-18 20:48       ` [PATCH 2/2] drm/i915: create a race-free reset detection Daniel Vetter
2013-01-21 12:06         ` Damien Lespiau
2013-01-21 19:15           ` Daniel Vetter
2012-12-05 14:54   ` [PATCH 1/2] drm/i915: clear up wedged transitions Damien Lespiau
2012-12-05 16:38   ` Damien Lespiau
2012-12-05 17:14     ` Daniel Vetter
2014-09-03 20:26   ` Chris Wilson [this message]
2014-09-04  6:03     ` Daniel Vetter
2014-09-04  6:11       ` Chris Wilson

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