[PATCH 12/12] drm/i915: Cache the reset_counter for the request

[Chris Wilson <chris@chris-wilson.co.uk>]

Instead of querying the reset counter before every access to the ring,
query it the first time we touch the ring, and do a final compare when
submitting the request. For correctness, we need to then sanitize how
the reset_counter is incremented to prevent broken submission and
waiting across resets, in the process fixing the persistent -EIO we
still see today on failed waits.

v2: Rebase
v3: Now with added testcase

Testcase: igt/gem_eio
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_debugfs.c     |  2 +-
 drivers/gpu/drm/i915/i915_drv.c         | 32 +++++++-----
 drivers/gpu/drm/i915/i915_drv.h         | 39 ++++++++++----
 drivers/gpu/drm/i915/i915_gem.c         | 90 +++++++++++++++------------------
 drivers/gpu/drm/i915/i915_irq.c         | 21 +-------
 drivers/gpu/drm/i915/intel_display.c    | 10 ++--
 drivers/gpu/drm/i915/intel_ringbuffer.c | 17 ++++---
 7 files changed, 104 insertions(+), 107 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index d83f35c8df34..107711ec956f 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -4415,7 +4415,7 @@ i915_wedged_get(void *data, u64 *val)
 	struct drm_device *dev = data;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	*val = atomic_read(&dev_priv->gpu_error.reset_counter);
+	*val = i915_terminally_wedged(&dev_priv->gpu_error);
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index ffd99d27fac7..5838882e10a1 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -841,23 +841,31 @@ int i915_resume_legacy(struct drm_device *dev)
 int i915_reset(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct i915_gpu_error *error = &dev_priv->gpu_error;
+	unsigned reset_counter;
 	bool simulated;
 	int ret;
 
 	intel_reset_gt_powersave(dev);
 
 	mutex_lock(&dev->struct_mutex);
+	atomic_clear_mask(I915_WEDGED, &error->reset_counter);
+	reset_counter = atomic_inc_return(&error->reset_counter);
+	if (WARN_ON(__i915_reset_in_progress(reset_counter))) {
+		ret = -EIO;
+		goto error;
+	}
 
 	i915_gem_reset(dev);
 
-	simulated = dev_priv->gpu_error.stop_rings != 0;
+	simulated = error->stop_rings != 0;
 
 	ret = intel_gpu_reset(dev);
 
 	/* Also reset the gpu hangman. */
 	if (simulated) {
 		DRM_INFO("Simulated gpu hang, resetting stop_rings\n");
-		dev_priv->gpu_error.stop_rings = 0;
+		error->stop_rings = 0;
 		if (ret == -ENODEV) {
 			DRM_INFO("Reset not implemented, but ignoring "
 				 "error for simulated gpu hangs\n");
@@ -870,8 +878,7 @@ int i915_reset(struct drm_device *dev)
 
 	if (ret) {
 		DRM_ERROR("Failed to reset chip: %i\n", ret);
-		mutex_unlock(&dev->struct_mutex);
-		return ret;
+		goto error;
 	}
 
 	intel_overlay_reset(dev_priv);
@@ -890,20 +897,14 @@ int i915_reset(struct drm_device *dev)
 	 * was running at the time of the reset (i.e. we weren't VT
 	 * switched away).
 	 */
-
-	/* Used to prevent gem_check_wedged returning -EAGAIN during gpu reset */
-	dev_priv->gpu_error.reload_in_reset = true;
-
 	ret = i915_gem_init_hw(dev);
-
-	dev_priv->gpu_error.reload_in_reset = false;
-
-	mutex_unlock(&dev->struct_mutex);
 	if (ret) {
 		DRM_ERROR("Failed hw init on reset %d\n", ret);
-		return ret;
+		goto error;
 	}
 
+	mutex_unlock(&dev->struct_mutex);
+
 	/*
 	 * rps/rc6 re-init is necessary to restore state lost after the
 	 * reset and the re-install of gt irqs. Skip for ironlake per
@@ -914,6 +915,11 @@ int i915_reset(struct drm_device *dev)
 		intel_enable_gt_powersave(dev);
 
 	return 0;
+
+error:
+	atomic_set_mask(I915_WEDGED, &error->reset_counter);
+	mutex_unlock(&dev->struct_mutex);
+	return ret;
 }
 
 static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 3fe933e4e664..aa83b284cb2f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1395,9 +1395,6 @@ struct i915_gpu_error {
 
 	/* For missed irq/seqno simulation. */
 	unsigned int test_irq_rings;
-
-	/* Used to prevent gem_check_wedged returning -EAGAIN during gpu reset   */
-	bool reload_in_reset;
 };
 
 enum modeset_restore {
@@ -2157,6 +2154,7 @@ struct drm_i915_gem_request {
 	/** On Which ring this request was generated */
 	struct drm_i915_private *i915;
 	struct intel_engine_cs *engine;
+	unsigned reset_counter;
 
 	/** GEM sequence number associated with this request. */
 	uint32_t seqno;
@@ -2891,23 +2889,47 @@ struct drm_i915_gem_request *
 i915_gem_find_active_request(struct intel_engine_cs *ring);
 
 bool i915_gem_retire_requests(struct drm_device *dev);
-int __must_check i915_gem_check_wedge(struct i915_gpu_error *error,
+int __must_check i915_gem_check_wedge(unsigned reset_counter,
 				      bool interruptible);
 
+static inline u32 i915_reset_counter(struct i915_gpu_error *error)
+{
+	return atomic_read(&error->reset_counter);
+}
+
+static inline bool __i915_reset_in_progress(u32 reset)
+{
+	return unlikely(reset & I915_RESET_IN_PROGRESS_FLAG);
+}
+
+static inline bool __i915_reset_in_progress_or_wedged(u32 reset)
+{
+	return unlikely(reset & (I915_RESET_IN_PROGRESS_FLAG | I915_WEDGED));
+}
+
+static inline bool __i915_terminally_wedged(u32 reset)
+{
+	return unlikely(reset & I915_WEDGED);
+}
+
 static inline bool i915_reset_in_progress(struct i915_gpu_error *error)
 {
-	return unlikely(atomic_read(&error->reset_counter)
-			& (I915_RESET_IN_PROGRESS_FLAG | I915_WEDGED));
+	return __i915_reset_in_progress(i915_reset_counter(error));
+}
+
+static inline bool i915_reset_in_progress_or_wedged(struct i915_gpu_error *error)
+{
+	return __i915_reset_in_progress_or_wedged(i915_reset_counter(error));
 }
 
 static inline bool i915_terminally_wedged(struct i915_gpu_error *error)
 {
-	return atomic_read(&error->reset_counter) & I915_WEDGED;
+	return __i915_terminally_wedged(i915_reset_counter(error));
 }
 
 static inline u32 i915_reset_count(struct i915_gpu_error *error)
 {
-	return ((atomic_read(&error->reset_counter) & ~I915_WEDGED) + 1) / 2;
+	return ((i915_reset_counter(error) & ~I915_WEDGED) + 1) / 2;
 }
 
 static inline bool i915_stop_ring_allow_ban(struct drm_i915_private *dev_priv)
@@ -2940,7 +2962,6 @@ void __i915_add_request(struct drm_i915_gem_request *req,
 #define i915_add_request_no_flush(req) \
 	__i915_add_request(req, NULL, false)
 int __i915_wait_request(struct drm_i915_gem_request *req,
-			unsigned reset_counter,
 			bool interruptible,
 			s64 *timeout,
 			struct intel_rps_client *rps);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d3609e111647..6ac9c80244fa 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -85,9 +85,7 @@ i915_gem_wait_for_error(struct i915_gpu_error *error)
 {
 	int ret;
 
-#define EXIT_COND (!i915_reset_in_progress(error) || \
-		   i915_terminally_wedged(error))
-	if (EXIT_COND)
+	if (!i915_reset_in_progress(error))
 		return 0;
 
 	/*
@@ -96,17 +94,16 @@ i915_gem_wait_for_error(struct i915_gpu_error *error)
 	 * we should simply try to bail out and fail as gracefully as possible.
 	 */
 	ret = wait_event_interruptible_timeout(error->reset_queue,
-					       EXIT_COND,
+					       !i915_reset_in_progress(error),
 					       10*HZ);
 	if (ret == 0) {
 		DRM_ERROR("Timed out waiting for the gpu reset to complete\n");
 		return -EIO;
 	} else if (ret < 0) {
 		return ret;
+	} else {
+		return 0;
 	}
-#undef EXIT_COND
-
-	return 0;
 }
 
 int i915_mutex_lock_interruptible(struct drm_device *dev)
@@ -1112,26 +1109,20 @@ put_rpm:
 }
 
 int
-i915_gem_check_wedge(struct i915_gpu_error *error,
+i915_gem_check_wedge(unsigned reset_counter,
 		     bool interruptible)
 {
-	if (i915_reset_in_progress(error)) {
+	if (__i915_reset_in_progress_or_wedged(reset_counter)) {
 		/* Non-interruptible callers can't handle -EAGAIN, hence return
 		 * -EIO unconditionally for these. */
 		if (!interruptible)
 			return -EIO;
 
 		/* Recovery complete, but the reset failed ... */
-		if (i915_terminally_wedged(error))
+		if (__i915_terminally_wedged(reset_counter))
 			return -EIO;
 
-		/*
-		 * Check if GPU Reset is in progress - we need intel_ring_begin
-		 * to work properly to reinit the hw state while the gpu is
-		 * still marked as reset-in-progress. Handle this with a flag.
-		 */
-		if (!error->reload_in_reset)
-			return -EAGAIN;
+		return -EAGAIN;
 	}
 
 	return 0;
@@ -1200,7 +1191,6 @@ static int __i915_spin_request(struct drm_i915_gem_request *req, int state)
 /**
  * __i915_wait_request - wait until execution of request has finished
  * @req: duh!
- * @reset_counter: reset sequence associated with the given request
  * @interruptible: do an interruptible wait (normally yes)
  * @timeout: in - how long to wait (NULL forever); out - how much time remaining
  *
@@ -1215,7 +1205,6 @@ static int __i915_spin_request(struct drm_i915_gem_request *req, int state)
  * errno with remaining time filled in timeout argument.
  */
 int __i915_wait_request(struct drm_i915_gem_request *req,
-			unsigned reset_counter,
 			bool interruptible,
 			s64 *timeout,
 			struct intel_rps_client *rps)
@@ -1264,12 +1253,12 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
 
 		/* We need to check whether any gpu reset happened in between
 		 * the caller grabbing the seqno and now ... */
-		if (reset_counter != atomic_read(&dev_priv->gpu_error.reset_counter)) {
-			/* ... but upgrade the -EAGAIN to an -EIO if the gpu
-			 * is truely gone. */
-			ret = i915_gem_check_wedge(&dev_priv->gpu_error, interruptible);
-			if (ret == 0)
-				ret = -EAGAIN;
+		if (req->reset_counter != i915_reset_counter(&dev_priv->gpu_error)) {
+			/* As we do not requeue the request over a GPU reset,
+			 * if one does occur we know that the request is
+			 * effectively complete.
+			 */
+			ret = 0;
 			break;
 		}
 
@@ -1433,13 +1422,7 @@ i915_wait_request(struct drm_i915_gem_request *req)
 
 	BUG_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
 
-	ret = i915_gem_check_wedge(&dev_priv->gpu_error, interruptible);
-	if (ret)
-		return ret;
-
-	ret = __i915_wait_request(req,
-				  atomic_read(&dev_priv->gpu_error.reset_counter),
-				  interruptible, NULL, NULL);
+	ret = __i915_wait_request(req, interruptible, NULL, NULL);
 	if (ret)
 		return ret;
 
@@ -1514,7 +1497,6 @@ i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
 	struct drm_device *dev = obj->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_request *requests[I915_NUM_RINGS];
-	unsigned reset_counter;
 	int ret, i, n = 0;
 
 	BUG_ON(!mutex_is_locked(&dev->struct_mutex));
@@ -1523,12 +1505,6 @@ i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
 	if (!obj->active)
 		return 0;
 
-	ret = i915_gem_check_wedge(&dev_priv->gpu_error, true);
-	if (ret)
-		return ret;
-
-	reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
-
 	if (readonly) {
 		struct drm_i915_gem_request *req;
 
@@ -1550,9 +1526,9 @@ i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
 	}
 
 	mutex_unlock(&dev->struct_mutex);
+	ret = 0;
 	for (i = 0; ret == 0 && i < n; i++)
-		ret = __i915_wait_request(requests[i], reset_counter, true,
-					  NULL, rps);
+		ret = __i915_wait_request(requests[i], true, NULL, rps);
 	mutex_lock(&dev->struct_mutex);
 
 	for (i = 0; i < n; i++) {
@@ -2707,6 +2683,7 @@ int i915_gem_request_alloc(struct intel_engine_cs *engine,
 			   struct drm_i915_gem_request **req_out)
 {
 	struct drm_i915_private *dev_priv = to_i915(engine->dev);
+	unsigned reset_counter = i915_reset_counter(&dev_priv->gpu_error);
 	struct drm_i915_gem_request *req;
 	int ret;
 
@@ -2715,6 +2692,10 @@ int i915_gem_request_alloc(struct intel_engine_cs *engine,
 
 	*req_out = NULL;
 
+	ret = i915_gem_check_wedge(reset_counter, dev_priv->mm.interruptible);
+	if (ret)
+		return ret;
+
 	req = kmem_cache_zalloc(dev_priv->requests, GFP_KERNEL);
 	if (req == NULL)
 		return -ENOMEM;
@@ -2725,6 +2706,7 @@ int i915_gem_request_alloc(struct intel_engine_cs *engine,
 
 	kref_init(&req->ref);
 	req->i915 = dev_priv;
+	req->reset_counter = reset_counter;
 	req->engine = engine;
 	req->ctx  = ctx;
 	i915_gem_context_reference(req->ctx);
@@ -3077,11 +3059,9 @@ void i915_gem_close_object(struct drm_gem_object *gem,
 int
 i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 {
-	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_wait *args = data;
 	struct drm_i915_gem_object *obj;
 	struct drm_i915_gem_request *req[I915_NUM_RINGS];
-	unsigned reset_counter;
 	int i, n = 0;
 	int ret;
 
@@ -3115,7 +3095,6 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 	}
 
 	drm_gem_object_unreference(&obj->base);
-	reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
 
 	for (i = 0; i < I915_NUM_RINGS; i++) {
 		if (obj->last_read_req[i] == NULL)
@@ -3128,11 +3107,23 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 
 	for (i = 0; i < n; i++) {
 		if (ret == 0)
-			ret = __i915_wait_request(req[i], reset_counter, true,
+			ret = __i915_wait_request(req[i], true,
 						  args->timeout_ns > 0 ? &args->timeout_ns : NULL,
 						  file->driver_priv);
+
+		/* If the GPU hung before this, report it. Ideally we only
+		 * report if this request cannot be completed. Currently
+		 * when we don't mark the guilty party and abort all
+		 * requests on reset, so just mark all as EIO.
+		 */
+		if (ret == 0 &&
+		    req[i]->reset_counter != i915_reset_counter(&req[i]->i915->gpu_error))
+			ret = -EIO;
+
 		i915_gem_request_unreference__unlocked(req[i]);
 	}
+
+
 	return ret;
 
 out:
@@ -3160,7 +3151,6 @@ __i915_gem_object_sync(struct drm_i915_gem_object *obj,
 	if (!i915_semaphore_is_enabled(from_req->i915)) {
 		struct drm_i915_private *i915 = from_req->i915;
 		ret = __i915_wait_request(from_req,
-					  atomic_read(&i915->gpu_error.reset_counter),
 					  i915->mm.interruptible,
 					  NULL,
 					  &i915->rps.semaphores);
@@ -4082,14 +4072,15 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
 	struct drm_i915_file_private *file_priv = file->driver_priv;
 	unsigned long recent_enough = jiffies - DRM_I915_THROTTLE_JIFFIES;
 	struct drm_i915_gem_request *request, *target = NULL;
-	unsigned reset_counter;
 	int ret;
 
 	ret = i915_gem_wait_for_error(&dev_priv->gpu_error);
 	if (ret)
 		return ret;
 
-	ret = i915_gem_check_wedge(&dev_priv->gpu_error, false);
+	/* ABI: return -EIO if wedged */
+	ret = i915_gem_check_wedge(i915_reset_counter(&dev_priv->gpu_error),
+				   false);
 	if (ret)
 		return ret;
 
@@ -4107,7 +4098,6 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
 
 		target = request;
 	}
-	reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
 	if (target)
 		i915_gem_request_reference(target);
 	spin_unlock(&file_priv->mm.lock);
@@ -4115,7 +4105,7 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
 	if (target == NULL)
 		return 0;
 
-	ret = __i915_wait_request(target, reset_counter, true, NULL, NULL);
+	ret = __i915_wait_request(target, true, NULL, NULL);
 	if (ret == 0)
 		queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, 0);
 
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index f9f5e9cf7360..186315208462 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2200,7 +2200,6 @@ static void i915_error_wake_up(struct drm_i915_private *dev_priv,
 static void i915_reset_and_wakeup(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
-	struct i915_gpu_error *error = &dev_priv->gpu_error;
 	char *error_event[] = { I915_ERROR_UEVENT "=1", NULL };
 	char *reset_event[] = { I915_RESET_UEVENT "=1", NULL };
 	char *reset_done_event[] = { I915_ERROR_UEVENT "=0", NULL };
@@ -2218,7 +2217,7 @@ static void i915_reset_and_wakeup(struct drm_device *dev)
 	 * the reset in-progress bit is only ever set by code outside of this
 	 * work we don't need to worry about any other races.
 	 */
-	if (i915_reset_in_progress(error) && !i915_terminally_wedged(error)) {
+	if (i915_reset_in_progress(&dev_priv->gpu_error)) {
 		DRM_DEBUG_DRIVER("resetting chip\n");
 		kobject_uevent_env(&dev->primary->kdev->kobj, KOBJ_CHANGE,
 				   reset_event);
@@ -2246,25 +2245,9 @@ static void i915_reset_and_wakeup(struct drm_device *dev)
 
 		intel_runtime_pm_put(dev_priv);
 
-		if (ret == 0) {
-			/*
-			 * After all the gem state is reset, increment the reset
-			 * counter and wake up everyone waiting for the reset to
-			 * complete.
-			 *
-			 * Since unlock operations are a one-sided barrier only,
-			 * we need to insert a barrier here to order any seqno
-			 * updates before
-			 * the counter increment.
-			 */
-			smp_mb__before_atomic();
-			atomic_inc(&dev_priv->gpu_error.reset_counter);
-
+		if (ret == 0)
 			kobject_uevent_env(&dev->primary->kdev->kobj,
 					   KOBJ_CHANGE, reset_done_event);
-		} else {
-			atomic_set_mask(I915_WEDGED, &error->reset_counter);
-		}
 
 		/*
 		 * Note: The wake_up also serves as a memory barrier so that
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index cdd6074257af..8cb89320d28d 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3298,8 +3298,7 @@ static bool intel_crtc_has_pending_flip(struct drm_crtc *crtc)
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	bool pending;
 
-	if (i915_reset_in_progress(&dev_priv->gpu_error) ||
-	    intel_crtc->reset_counter != atomic_read(&dev_priv->gpu_error.reset_counter))
+	if (intel_crtc->reset_counter != i915_reset_counter(&dev_priv->gpu_error))
 		return false;
 
 	spin_lock_irq(&dev->event_lock);
@@ -10751,8 +10750,7 @@ static bool page_flip_finished(struct intel_crtc *crtc)
 	struct drm_device *dev = crtc->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	if (i915_reset_in_progress(&dev_priv->gpu_error) ||
-	    crtc->reset_counter != atomic_read(&dev_priv->gpu_error.reset_counter))
+	if (crtc->reset_counter != i915_reset_counter(&dev_priv->gpu_error))
 		return true;
 
 	/*
@@ -11180,9 +11178,7 @@ static void intel_mmio_flip_work_func(struct work_struct *work)
 		container_of(work, struct intel_mmio_flip, work);
 
 	if (mmio_flip->req)
-		WARN_ON(__i915_wait_request(mmio_flip->req,
-					    mmio_flip->crtc->reset_counter,
-					    false, NULL,
+		WARN_ON(__i915_wait_request(mmio_flip->req, false, NULL,
 					    &mmio_flip->i915->rps.mmioflips));
 
 	intel_do_mmio_flip(mmio_flip->crtc);
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index f33db3495e35..b3538b66353b 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -2156,9 +2156,7 @@ int intel_ring_idle(struct intel_engine_cs *ring)
 			list);
 
 	/* Make sure we do not trigger any retires */
-	return __i915_wait_request(req,
-				   atomic_read(&req->i915->gpu_error.reset_counter),
-				   req->i915->mm.interruptible,
+	return __i915_wait_request(req, req->i915->mm.interruptible,
 				   NULL, NULL);
 }
 
@@ -2252,6 +2250,14 @@ static int wait_for_space(struct drm_i915_gem_request *req, int bytes)
 	if (ret)
 		return ret;
 
+	/* If the request was completed due to a GPU hang, we want to
+	 * error out before we continue to emit more commands to the GPU.
+	 */
+	ret = i915_gem_check_wedge(i915_reset_counter(&to_i915(engine->dev)->gpu_error),
+				   to_i915(engine->dev)->mm.interruptible);
+	if (ret)
+		return ret;
+
 	ring->space = space;
 	return 0;
 }
@@ -2316,11 +2322,6 @@ int intel_ring_begin(struct drm_i915_gem_request *req, int num_dwords)
 {
 	int ret;
 
-	ret = i915_gem_check_wedge(&req->i915->gpu_error,
-				   req->i915->mm.interruptible);
-	if (ret)
-		return ret;
-
 	ret = ring_prepare(req, num_dwords * sizeof(uint32_t));
 	if (ret)
 		return ret;
-- 
2.6.2

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