From f70b69dbe2b62a47930dce23d895a3e0128ebad8 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu, 21 Nov 2019 10:35:46 +0000
Subject: drm/i915/execlists: Lock the request while validating it during
Git-commit: c95d31c3df1b9ff29bcd85c47324e16d430bbd5a
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
 promotion

Since the request is already on the HW as we perform its validation, it
and even its subsequent barrier may be concurrently retired before we
process the assertions. If it is retired already and so off the HW, our
assertions become void and we need to ignore them.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112363
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191121103546.146487-1-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/gt/intel_lrc.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index f51107e566eb..f8a2977723f2 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1306,38 +1306,53 @@ assert_pending_valid(const struct intel_engine_execlists *execlists,
 	}
 
 	for (port = execlists->pending; (rq = *port); port++) {
+		unsigned long flags;
+		bool ok = true;
+
 		if (ce == rq->hw_context) {
 			GEM_TRACE_ERR("Dup context:%llx in pending[%zd]\n",
 				      ce->timeline->fence_context,
 				      port - execlists->pending);
 			return false;
 		}
-
 		ce = rq->hw_context;
+
+		/* Hold tightly onto the lock to prevent concurrent retires! */
+		spin_lock_irqsave_nested(&rq->lock, flags,
+					 SINGLE_DEPTH_NESTING);
+
 		if (i915_request_completed(rq))
-			continue;
+			goto unlock;
 
 		if (i915_active_is_idle(&ce->active) &&
 		    !i915_gem_context_is_kernel(ce->gem_context)) {
 			GEM_TRACE_ERR("Inactive context:%llx in pending[%zd]\n",
 				      ce->timeline->fence_context,
 				      port - execlists->pending);
-			return false;
+			ok = false;
+			goto unlock;
 		}
 
 		if (!i915_vma_is_pinned(ce->state)) {
 			GEM_TRACE_ERR("Unpinned context:%llx in pending[%zd]\n",
 				      ce->timeline->fence_context,
 				      port - execlists->pending);
-			return false;
+			ok = false;
+			goto unlock;
 		}
 
 		if (!i915_vma_is_pinned(ce->ring->vma)) {
 			GEM_TRACE_ERR("Unpinned ring:%llx in pending[%zd]\n",
 				      ce->timeline->fence_context,
 				      port - execlists->pending);
-			return false;
+			ok = false;
+			goto unlock;
 		}
+
+unlock:
+		spin_unlock_irqrestore(&rq->lock, flags);
+		if (!ok)
+			return false;
 	}
 
 	return ce;
-- 
2.28.0