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[CI,2/8] drm/i915: Only sync tasklets once for recursive reset preparation

Message ID 20180516183355.10553-2-chris@chris-wilson.co.uk (mailing list archive)
State New, archived
Headers show

Commit Message

Chris Wilson May 16, 2018, 6:33 p.m. UTC 
When setting up reset, we may need to recursively prepare an engine. In
which case we should only synchronously flush the tasklets on the outer
most call, the inner calls will then be inside an atomic section where
the tasklet will never be run (and so the sync will never complete).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 2 +-
 drivers/gpu/drm/i915/i915_gem.h | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)
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Patch

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0dc369a9ec4d..982393907b80 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3036,7 +3036,7 @@  i915_gem_reset_prepare_engine(struct intel_engine_cs *engine)
 	 * Turning off the execlists->tasklet until the reset is over
 	 * prevents the race.
 	 */
-	tasklet_disable(&engine->execlists.tasklet);
+	__tasklet_disable_sync_once(&engine->execlists.tasklet);
 
 	/*
 	 * We're using worker to queue preemption requests from the tasklet in
diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
index 525920404ede..5bf24cfc218c 100644
--- a/drivers/gpu/drm/i915/i915_gem.h
+++ b/drivers/gpu/drm/i915/i915_gem.h
@@ -26,6 +26,7 @@ 
 #define __I915_GEM_H__
 
 #include <linux/bug.h>
+#include <linux/interrupt.h>
 
 struct drm_i915_private;
 
@@ -72,4 +73,10 @@  struct drm_i915_private;
 void i915_gem_park(struct drm_i915_private *i915);
 void i915_gem_unpark(struct drm_i915_private *i915);
 
+static inline void __tasklet_disable_sync_once(struct tasklet_struct *t)
+{
+	if (atomic_inc_return(&t->count) == 1)
+		tasklet_unlock_wait(t);
+}
+
 #endif /* __I915_GEM_H__ */