drm/i915: Record the in-flight requests at the time of a hang

Being able to tally the list of outstanding requests with the sequence
of commands in the ringbuffer is often useful evidence with respect to
driver corruption.

Note that since this is the umpteenth per-ring data structure to be added
to the error state, I've coallesced the nearby loops (the ringbuffer and
batchbuffer) into a single structure along with the list of requests.  A
later task would be to refactor the ring register state into the same
structure.

v2: Fix pretty printing of requests so that they are parsed correctly by
intel_error_decode and use the 0x%08x format for seqno for consistency
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -738,7 +738,7 @@ static int i915_error_state(struct seq_file *m, void *unused)
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	struct drm_i915_error_state *error;
 	unsigned long flags;
-	int i, page, offset, elt;
+	int i, j, page, offset, elt;
 
 	spin_lock_irqsave(&dev_priv->error_lock, flags);
 	if (!dev_priv->first_error) {
@@ -778,10 +778,10 @@ static int i915_error_state(struct seq_file *m, void *unused)
 				    error->pinned_bo,
 				    error->pinned_bo_count);
 
-	for (i = 0; i < ARRAY_SIZE(error->batchbuffer); i++) {
-		if (error->batchbuffer[i]) {
-			struct drm_i915_error_object *obj = error->batchbuffer[i];
+	for (i = 0; i < ARRAY_SIZE(error->ring); i++) {
+		struct drm_i915_error_object *obj;
 
+		if ((obj = error->ring[i].batchbuffer)) {
 			seq_printf(m, "%s --- gtt_offset = 0x%08x\n",
 				   dev_priv->ring[i].name,
 				   obj->gtt_offset);
@@ -793,11 +793,19 @@ static int i915_error_state(struct seq_file *m, void *unused)
 				}
 			}
 		}
+
+		if (error->ring[i].num_requests) {
+			seq_printf(m, "%s --- %d requests\n",
+				   dev_priv->ring[i].name,
+				   error->ring[i].num_requests);
+			for (j = 0; j < error->ring[i].num_requests; j++) {
+				seq_printf(m, "  seqno 0x%08x, emitted %ld\n",
+					   error->ring[i].requests[j].seqno,
+					   error->ring[i].requests[j].jiffies);
+			}
 		}
 
-	for (i = 0; i < ARRAY_SIZE(error->ringbuffer); i++) {
-		if (error->ringbuffer[i]) {
-			struct drm_i915_error_object *obj = error->ringbuffer[i];
+		if ((obj = error->ring[i].ringbuffer)) {
 			seq_printf(m, "%s --- ringbuffer = 0x%08x\n",
 				   dev_priv->ring[i].name,
 				   obj->gtt_offset);

drivers/gpu/drm/i915/i915_drv.h

@@ -174,11 +174,18 @@ struct drm_i915_error_state {
 	u32 faddr[I915_NUM_RINGS];
 	u64 fence[I915_MAX_NUM_FENCES];
 	struct timeval time;
+	struct drm_i915_error_ring {
 		struct drm_i915_error_object {
 			int page_count;
 			u32 gtt_offset;
 			u32 *pages[0];
-	} *ringbuffer[I915_NUM_RINGS], *batchbuffer[I915_NUM_RINGS];
+		} *ringbuffer, *batchbuffer;
+		struct drm_i915_error_request {
+			long jiffies;
+			u32 seqno;
+		} *requests;
+		int num_requests;
+	} ring[I915_NUM_RINGS];
 	struct drm_i915_error_buffer {
 		u32 size;
 		u32 name;

drivers/gpu/drm/i915/i915_irq.c

@@ -788,11 +788,11 @@ i915_error_state_free(struct drm_device *dev,
 {
 	int i;
 
-	for (i = 0; i < ARRAY_SIZE(error->batchbuffer); i++)
-		i915_error_object_free(error->batchbuffer[i]);
-
-	for (i = 0; i < ARRAY_SIZE(error->ringbuffer); i++)
-		i915_error_object_free(error->ringbuffer[i]);
+	for (i = 0; i < ARRAY_SIZE(error->ring); i++) {
+		i915_error_object_free(error->ring[i].batchbuffer);
+		i915_error_object_free(error->ring[i].ringbuffer);
+		kfree(error->ring[i].requests);
+	}
 
 	kfree(error->active_bo);
 	kfree(error->overlay);
@@ -934,6 +934,51 @@ static void i915_record_ring_state(struct drm_device *dev,
 	error->cpu_ring_tail[ring->id] = ring->tail;
 }
 
+static void i915_gem_record_rings(struct drm_device *dev,
+				  struct drm_i915_error_state *error)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_i915_gem_request *request;
+	int i, count;
+
+	for (i = 0; i < I915_NUM_RINGS; i++) {
+		struct intel_ring_buffer *ring = &dev_priv->ring[i];
+
+		if (ring->obj == NULL)
+			continue;
+
+		i915_record_ring_state(dev, error, ring);
+
+		error->ring[i].batchbuffer =
+			i915_error_first_batchbuffer(dev_priv, ring);
+
+		error->ring[i].ringbuffer =
+			i915_error_object_create(dev_priv, ring->obj);
+
+		count = 0;
+		list_for_each_entry(request, &ring->request_list, list)
+			count++;
+
+		error->ring[i].num_requests = count;
+		error->ring[i].requests =
+			kmalloc(count*sizeof(struct drm_i915_error_request),
+				GFP_ATOMIC);
+		if (error->ring[i].requests == NULL) {
+			error->ring[i].num_requests = 0;
+			continue;
+		}
+
+		count = 0;
+		list_for_each_entry(request, &ring->request_list, list) {
+			struct drm_i915_error_request *erq;
+
+			erq = &error->ring[i].requests[count++];
+			erq->seqno = request->seqno;
+			erq->jiffies = request->emitted_jiffies;
+		}
+	}
+}
+
 /**
  * i915_capture_error_state - capture an error record for later analysis
  * @dev: drm device
@@ -977,24 +1022,8 @@ static void i915_capture_error_state(struct drm_device *dev)
 		error->done_reg = I915_READ(DONE_REG);
 	}
 
-	i915_record_ring_state(dev, error, &dev_priv->ring[RCS]);
-	if (HAS_BLT(dev))
-		i915_record_ring_state(dev, error, &dev_priv->ring[BCS]);
-	if (HAS_BSD(dev))
-		i915_record_ring_state(dev, error, &dev_priv->ring[VCS]);
-
 	i915_gem_record_fences(dev, error);
-
-	/* Record the active batch and ring buffers */
-	for (i = 0; i < I915_NUM_RINGS; i++) {
-		error->batchbuffer[i] =
-			i915_error_first_batchbuffer(dev_priv,
-						     &dev_priv->ring[i]);
-
-		error->ringbuffer[i] =
-			i915_error_object_create(dev_priv,
-						 dev_priv->ring[i].obj);
-	}
+	i915_gem_record_rings(dev, error);
 
 	/* Record buffers on the active and pinned lists. */
 	error->active_bo = NULL;