diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index a53777dd371c37..8f88851a9306e2 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -194,6 +194,27 @@ static void free_capture_list(struct i915_request *request) } } +static void remove_from_engine(struct i915_request *rq) +{ + struct intel_engine_cs *engine, *locked; + + /* + * Virtual engines complicate acquiring the engine timeline lock, + * as their rq->engine pointer is not stable until under that + * engine lock. The simple ploy we use is to take the lock then + * check that the rq still belongs to the newly locked engine. + */ + locked = READ_ONCE(rq->engine); + spin_lock(&locked->active.lock); + while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) { + spin_unlock(&locked->active.lock); + spin_lock(&engine->active.lock); + locked = engine; + } + list_del(&rq->sched.link); + spin_unlock(&locked->active.lock); +} + static bool i915_request_retire(struct i915_request *rq) { struct i915_active_request *active, *next; @@ -259,9 +280,7 @@ static bool i915_request_retire(struct i915_request *rq) * request that we have removed from the HW and put back on a run * queue. */ - spin_lock(&rq->engine->active.lock); - list_del(&rq->sched.link); - spin_unlock(&rq->engine->active.lock); + remove_from_engine(rq); spin_lock(&rq->lock); i915_request_mark_complete(rq);