[Intel-gfx] [PATCH] drm/i915: Check hangcheck is functioning before indefinite waits

[Chris Wilson]

Since we rely on hangcheck to wait up and kick us out of an indefinite
wait should the GPU ever stop functioning, it appears sensible that we
should check that hangcheck is indeed active before starting that wait.
This just prevents a driver error in the processing of hangcheck from
appearing to hang the machine.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.h         |  1 +
 drivers/gpu/drm/i915/i915_gem.c         |  2 ++
 drivers/gpu/drm/i915/i915_irq.c         | 11 +++++++++++
 drivers/gpu/drm/i915/intel_ringbuffer.c |  2 ++
 4 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8670d05..c326a99 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2149,6 +2149,7 @@ extern void intel_console_resume(struct work_struct *work);
 
 /* i915_irq.c */
 void i915_queue_hangcheck(struct drm_device *dev);
+void i915_check_hangcheck(struct drm_device *dev);
 __printf(3, 4)
 void i915_handle_error(struct drm_device *dev, bool wedged,
 		       const char *fmt, ...);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index ecb835b..120ed6d 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1455,6 +1455,8 @@ static int __wait_seqno(struct intel_engine_cs *ring, u32 seqno,
 			break;
 		}
 
+		i915_check_hangcheck(ring->dev);
+
 		timer.function = NULL;
 		if (timeout || missed_irq(dev_priv, ring)) {
 			unsigned long expire;
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 9e5a295..daa590e 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -3063,6 +3063,17 @@ void i915_queue_hangcheck(struct drm_device *dev)
 		  round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES));
 }
 
+void i915_check_hangcheck(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	if (!i915.enable_hangcheck)
+		return;
+
+	if (!timer_pending(&dev_priv->gpu_error.hangcheck_timer))
+		mod_timer(&dev_priv->gpu_error.hangcheck_timer,
+			  round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES));
+}
+
 static void ibx_irq_reset(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 4f3397f..6365d4d 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1634,6 +1634,8 @@ static int ring_wait_for_space(struct intel_engine_cs *ring, int n)
 				master_priv->sarea_priv->perf_boxes |= I915_BOX_WAIT;
 		}
 
+		i915_check_hangcheck(dev);
+
 		io_schedule_timeout(1);
 
 		if (dev_priv->mm.interruptible && signal_pending(current)) {
-- 
1.9.1