[Intel-gfx] [PATCH 2/3] drm/i915: Seek only one guilty batch per hanged ring

[Mika Kuoppala]

Instead of going through all the requests to find a batch that
hanged the machine, use hangcheck score and the fact that
first noncompleted request on hanged ring is, with great
probability, the guilty one. This also ensure that we get one
guilty batch per hang instead of possibly more (for each ring)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=73652
Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c         |   19 ++++++++++---------
 drivers/gpu/drm/i915/i915_irq.c         |    3 +--
 drivers/gpu/drm/i915/intel_ringbuffer.h |    2 ++
 3 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d270351..27a97c3 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2322,20 +2322,17 @@ static bool i915_context_is_banned(const struct i915_ctx_hang_stats *hs)
 
 static void i915_set_reset_status(struct intel_ring_buffer *ring,
 				  struct drm_i915_gem_request *request,
-				  u32 acthd)
+				  u32 acthd, const bool guilty)
 {
 	struct i915_ctx_hang_stats *hs = NULL;
-	bool inside, guilty;
+	bool inside;
 	unsigned long offset = 0;
 
-	/* Innocent until proven guilty */
-	guilty = false;
-
 	if (request->batch_obj)
 		offset = i915_gem_obj_offset(request->batch_obj,
 					     request_to_vm(request));
 
-	if (ring->hangcheck.action != HANGCHECK_WAIT &&
+	if (guilty &&
 	    i915_request_guilty(request, acthd, &inside)) {
 		DRM_DEBUG("%s hung %s bo (0x%lx ctx %d) at 0x%x\n",
 			  ring->name,
@@ -2343,8 +2340,6 @@ static void i915_set_reset_status(struct intel_ring_buffer *ring,
 			  offset,
 			  request->ctx ? request->ctx->id : 0,
 			  acthd);
-
-		guilty = true;
 	}
 
 	/* If contexts are disabled or this is the default context, use
@@ -2383,12 +2378,18 @@ static void i915_gem_reset_ring_status(struct drm_i915_private *dev_priv,
 	u32 completed_seqno = ring->get_seqno(ring, false);
 	u32 acthd = intel_ring_get_active_head(ring);
 	struct drm_i915_gem_request *request;
+	bool guilty = false;
 
 	list_for_each_entry(request, &ring->request_list, list) {
 		if (i915_seqno_passed(completed_seqno, request->seqno))
 			continue;
 
-		i915_set_reset_status(ring, request, acthd);
+		if (!guilty && ring->hangcheck.score >= HANGCHECK_SCORE_GUILTY) {
+			guilty = true;
+			i915_set_reset_status(ring, request, acthd, true);
+		} else {
+			i915_set_reset_status(ring, request, acthd, false);
+		}
 	}
 }
 
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 6d11e25..e24f9ef 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2473,7 +2473,6 @@ static void i915_hangcheck_elapsed(unsigned long data)
 #define BUSY 1
 #define KICK 5
 #define HUNG 20
-#define FIRE 30
 
 	if (!i915_enable_hangcheck)
 		return;
@@ -2557,7 +2556,7 @@ static void i915_hangcheck_elapsed(unsigned long data)
 	}
 
 	for_each_ring(ring, dev_priv, i) {
-		if (ring->hangcheck.score > FIRE) {
+		if (ring->hangcheck.score >= HANGCHECK_SCORE_GUILTY) {
 			DRM_INFO("%s on %s\n",
 				 stuck[i] ? "stuck" : "no progress",
 				 ring->name);
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 71a73f4..6018793 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -41,6 +41,8 @@ enum intel_ring_hangcheck_action {
 	HANGCHECK_HUNG,
 };
 
+#define HANGCHECK_SCORE_GUILTY 31
+
 struct intel_ring_hangcheck {
 	bool deadlock;
 	u32 seqno;
-- 
1.7.9.5