drm/i915: Only sync tasklets once for recursive reset preparation

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>
Link: https://patchwork.freedesktop.org/patch/msgid/20180516183355.10553-2-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0dc369a9ec4d04942f4c592a35cb882d832eaa7c..982393907b8065da3d371f034a382c235a0b8e91 100644 (file)
--- 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 525920404ede44b18da84d7947ecee8345bf7f6b..5bf24cfc218ccac79ef5a79a54119cf0be5cf5e6 100644 (file)
--- 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__ */