drm/i915: Clear the last_retired_context following a hang/reset

Following a hang and reset, we know that the engine is idle and all
context state has been saved or lost. Consequently, we know that the
engine is no longer referencing the last context and we can relinquish
our tracking.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Tvrtko Ursulin <tursulin@ursulin.net>
Link: http://patchwork.freedesktop.org/patch/msgid/20170212172002.23072-5-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 730804ce96106c21a8fe138f8268694403363adb..638b335e72b6e03c20b6e18ee23dfe4d4159449a 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2788,8 +2788,14 @@ void i915_gem_reset(struct drm_i915_private *dev_priv)
 
        i915_gem_retire_requests(dev_priv);
 
-       for_each_engine(engine, dev_priv, id)
+       for_each_engine(engine, dev_priv, id) {
+               struct i915_gem_context *ctx;
+
                i915_gem_reset_engine(engine);
+               ctx = fetch_and_zero(&engine->last_retired_context);
+               if (ctx)
+                       engine->context_unpin(engine, ctx);
+       }
 
        i915_gem_restore_fences(dev_priv);