linux-kernel - [152/200] drm/i915: Kill dangerous pending-flip debugging

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Date:	Thu, 01 Jul 2010 10:44:02 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Chris Wilson <chris@...is-wilson.co.uk>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Eric Anholt <eric@...olt.net>
Subject: [152/200] drm/i915: Kill dangerous pending-flip debugging

2.6.34-stable review patch.  If anyone has any objections, please let me know.

------------------

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

commit 9908ff736adf261e749b4887486a32ffa209304c upstream.

We can, by virtue of a vblank interrupt firing in the middle of setting
up the unpin work (i.e. after we set the unpin_work field and before we
write to the ringbuffer) enter intel_finish_page_flip() prior to
receiving the pending flip notification. Therefore we can expect to hit
intel_finish_page_flip() under normal circumstances without a pending flip
and even without installing the pending_flip_obj. This is exacerbated by
aperture thrashing whilst binding the framebuffer


  Bug 28079 - "glresize" causes kernel panic in intel_finish_page_flip.
  https://bugs.freedesktop.org/show_bug.cgi?id=28079

Reported-by: Nick Bowler <nbowler@...conx.ca>
Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@...tuousgeek.org>
Reviewed-by: Jesse Barnes <jbarnes@...tuousgeek.org>
Signed-off-by: Eric Anholt <eric@...olt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/gpu/drm/i915/intel_display.c |    6 ------
 1 file changed, 6 deletions(-)

--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4155,12 +4155,6 @@ void intel_finish_page_flip(struct drm_d
 	spin_lock_irqsave(&dev->event_lock, flags);
 	work = intel_crtc->unpin_work;
 	if (work == NULL || !work->pending) {
-		if (work && !work->pending) {
-			obj_priv = to_intel_bo(work->pending_flip_obj);
-			DRM_DEBUG_DRIVER("flip finish: %p (%d) not pending?\n",
-					 obj_priv,
-					 atomic_read(&obj_priv->pending_flip));
-		}
 		spin_unlock_irqrestore(&dev->event_lock, flags);
 		return;
 	}


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