[Intel-gfx] [PATCH] drm/i915: Order two completing nop_submit_request

[Chris Wilson]

If two nop's (requests in-flight following a wedged device) complete at
the same time, the global_seqno value written to the HWSP is undefined
as the two threads are not serialized.

Fixes: ce1135c7de64 ("drm/i915: Complete requests in nop_submit_request")
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index ab8c6946fea4..2779bcaff82e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3016,8 +3016,11 @@ static void nop_submit_request(struct drm_i915_gem_request *request)
 {
 	GEM_BUG_ON(!i915_terminally_wedged(&request->i915->gpu_error));
 	dma_fence_set_error(&request->fence, -EIO);
-	i915_gem_request_submit(request);
+
+	spin_lock_irq(&request->engine->timeline->lock);
+	__i915_gem_request_submit(request);
 	intel_engine_init_global_seqno(request->engine, request->global_seqno);
+	spin_unlock_irq(&request->engine->timeline->lock);
 }
 
 static void engine_set_wedged(struct intel_engine_cs *engine)
-- 
2.14.2