[PATCH 3/4] drm/i915: Do not short-circuit tasklets during reset

[Chris Wilson]

Inside intel_engine_is_idle(), we flush the tasklet to ensure that is
being run in a timely fashion (ksoftirqd has taught us to expect the
worst). However, if we are in the middle of reset, the HW may not yet be
ready to execute the submission tasklet and so we must respect the
disable flag.

Fixes: dd0cf235d81f ("drm/i915: Speed up idle detection by kicking the tasklets")
Testcase: igt/drv_selftest/live_hangcheck
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_engine_cs.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index 220050107c48..fccb95ea1315 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -989,16 +989,17 @@ bool intel_engine_is_idle(struct intel_engine_cs *engine)
 
 	/* Waiting to drain ELSP? */
 	if (READ_ONCE(engine->execlists.active)) {
-		struct intel_engine_execlists *execlists = &engine->execlists;
+		struct tasklet_struct *t = &engine->execlists.tasklet;
 
 		local_bh_disable();
-		if (tasklet_trylock(&execlists->tasklet)) {
-			execlists->tasklet.func(execlists->tasklet.data);
-			tasklet_unlock(&execlists->tasklet);
+		if (tasklet_trylock(t)) {
+			if (__tasklet_is_enabled(t))
+				t->func(t->data);
+			tasklet_unlock(t);
 		}
 		local_bh_enable();
 
-		if (READ_ONCE(execlists->active))
+		if (READ_ONCE(engine->execlists.active))
 			return false;
 	}
 
-- 
2.18.0