[Intel-gfx] [PATCH] drm/i915: Defer application of request banning to submission

[Chris Wilson]

As we currently do not check on submission whether the context is banned
in a timely manner it is possible for some requests to escape
cancellation after their parent context is banned. By moving the ban
into the request submission under the engine->timeline.lock, we
serialise it with the reset and setting of the context ban.

References: eb8d0f5af4ec ("drm/i915: Remove GPU reset dependence on struct_mutex")
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/i915_request.c |  3 +++
 drivers/gpu/drm/i915/i915_reset.c   | 19 +++++--------------
 2 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 0acd6baa3c88..5ab4e1c01618 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -366,6 +366,9 @@ void __i915_request_submit(struct i915_request *request)
 	GEM_BUG_ON(!irqs_disabled());
 	lockdep_assert_held(&engine->timeline.lock);
 
+	if (i915_gem_context_is_banned(request->gem_context))
+		i915_request_skip(request, -EIO);
+
 	GEM_BUG_ON(request->global_seqno);
 
 	seqno = next_global_seqno(&engine->timeline);
diff --git a/drivers/gpu/drm/i915/i915_reset.c b/drivers/gpu/drm/i915/i915_reset.c
index 12e74decd7a2..7fa97ce19bfd 100644
--- a/drivers/gpu/drm/i915/i915_reset.c
+++ b/drivers/gpu/drm/i915/i915_reset.c
@@ -22,24 +22,15 @@ static void engine_skip_context(struct i915_request *rq)
 {
 	struct intel_engine_cs *engine = rq->engine;
 	struct i915_gem_context *hung_ctx = rq->gem_context;
-	struct i915_timeline *timeline = rq->timeline;
 
 	lockdep_assert_held(&engine->timeline.lock);
-	GEM_BUG_ON(timeline == &engine->timeline);
 
-	spin_lock(&timeline->lock);
-
-	if (i915_request_is_active(rq)) {
-		list_for_each_entry_continue(rq,
-					     &engine->timeline.requests, link)
-			if (rq->gem_context == hung_ctx)
-				i915_request_skip(rq, -EIO);
-	}
-
-	list_for_each_entry(rq, &timeline->requests, link)
-		i915_request_skip(rq, -EIO);
+	if (!i915_request_is_active(rq))
+		return;
 
-	spin_unlock(&timeline->lock);
+	list_for_each_entry_continue(rq, &engine->timeline.requests, link)
+		if (rq->gem_context == hung_ctx)
+			i915_request_skip(rq, -EIO);
 }
 
 static void client_mark_guilty(struct drm_i915_file_private *file_priv,
-- 
2.20.1