From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri, 13 Jul 2018 21:35:28 +0100
Subject: drm/i915: Do not short-circuit tasklets during reset
Git-commit: 9701975e851082d179faaab9c6306a7800d86c0f
Patch-mainline: v4.19-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

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@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Michel Thierry <michel.thierry@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180713203529.1973-2-chris@chris-wilson.co.uk

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/i915/intel_engine_cs.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -989,16 +989,18 @@ bool intel_engine_is_idle(struct intel_e
 
 	/* 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)) {
+			/* Must wait for any GPU reset in progress. */
+			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;
 	}