[Intel-gfx] [PATCH] drm/i915: Don't continually defer the hangcheck

[Chris Wilson]

With multiple rings, we may continue to render on the blitter whilst
executing an infinite shader on the render ring. As we currently, rearm
the timer with each execbuf, in this scenario the hangcheck will never
fire and we will never detect the lockup on the render ring. Instead,
only arm the timer once per hangcheck, so that hangcheck runs more
frequently.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 318a6a0724d0..82b4d742aba5 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -3039,11 +3039,16 @@ static void i915_hangcheck_elapsed(unsigned long data)
 void i915_queue_hangcheck(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct timer_list *timer = &dev_priv->gpu_error.hangcheck_timer;
+
 	if (!i915.enable_hangcheck)
 		return;
 
-	mod_timer(&dev_priv->gpu_error.hangcheck_timer,
-		  round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES));
+	if (timer_pending(timer))
+		return;
+
+	timer->expires = round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES);
+	add_timer(timer);
 }
 
 static void ibx_irq_reset(struct drm_device *dev)
-- 
2.1.3