[Intel-gfx] [PATCH] drm/i915: Check that the breadcrumb wasn't disarmed automatically before parking

[Chris Wilson]

We will disarm the breadcrumb interrupt if we see a user interrupt
whilst no one is waiting. This may race with the call to
intel_engine_disarm_breadcrumbs() triggering an assert that we aren't
trying to do the same job twice. Prevent this by checking that the irq
is still armed after flushing the interrupt (for the irq spinlock).

Fixes: bcbd5c33a342 ("drm/i915/guc: Always enable the breadcrumbs irq")
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Michał Winiarski <michal.winiarski at intel.com>
---
 drivers/gpu/drm/i915/intel_breadcrumbs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
index 1bd0a461d665..4de054f8c1ba 100644
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -219,7 +219,8 @@ void intel_engine_disarm_breadcrumbs(struct intel_engine_cs *engine)
 
 	spin_lock(&b->irq_lock);
 	first = fetch_and_zero(&b->irq_wait);
-	__intel_engine_disarm_breadcrumbs(engine);
+	if (b->irq_armed)
+		__intel_engine_disarm_breadcrumbs(engine);
 	spin_unlock(&b->irq_lock);
 
 	rbtree_postorder_for_each_entry_safe(wait, n, &b->waiters, node) {
-- 
2.15.0.rc2