diff options
| -rw-r--r-- | drivers/gpu/drm/i915/i915_guc_submission.c | 12 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/intel_lrc.c | 12 |
2 files changed, 24 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c index a3636b31ebc3..832ac9e45801 100644 --- a/drivers/gpu/drm/i915/i915_guc_submission.c +++ b/drivers/gpu/drm/i915/i915_guc_submission.c @@ -577,6 +577,18 @@ static bool i915_guc_dequeue(struct intel_engine_cs *engine) struct rb_node *rb; bool submit = false; + /* After execlist_first is updated, the tasklet will be rescheduled. + * + * If we are currently running (inside the tasklet) and a third + * party queues a request and so updates engine->execlist_first under + * the spinlock (which we have elided), it will atomically set the + * TASKLET_SCHED flag causing the us to be re-executed and pick up + * the change in state (the update to TASKLET_SCHED incurs a memory + * barrier making this cross-cpu checking safe). + */ + if (!READ_ONCE(engine->execlist_first)) + return false; + spin_lock_irqsave(&engine->timeline->lock, flags); rb = engine->execlist_first; while (rb) { diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index becde55b02a3..77168e673e0a 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -403,6 +403,18 @@ static void execlists_dequeue(struct intel_engine_cs *engine) struct rb_node *rb; bool submit = false; + /* After execlist_first is updated, the tasklet will be rescheduled. + * + * If we are currently running (inside the tasklet) and a third + * party queues a request and so updates engine->execlist_first under + * the spinlock (which we have elided), it will atomically set the + * TASKLET_SCHED flag causing the us to be re-executed and pick up + * the change in state (the update to TASKLET_SCHED incurs a memory + * barrier making this cross-cpu checking safe). + */ + if (!READ_ONCE(engine->execlist_first)) + return; + last = port->request; if (last) /* WaIdleLiteRestore:bdw,skl |