drm/i915: Hold a reference on the request for its fence chain

Currently, we have an active reference for the request until it is
retired. Though it cannot be retired before it has been executed by
hardware, the request may be completed before we have finished
processing the execute fence, i.e. we may continue to process that fence
as we free the request.

Fixes: 5590af3e115a ("drm/i915: Drive request submission through fence callbacks")
Fixes: 23902e49c999 ("drm/i915: Split request submit/execute phase into two")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161125131718.20978-3-chris@chris-wilson.co.uk

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_sw_fence.h b/drivers/gpu/drm/i915/i915_sw_fence.h
index 7508d23f823b..0f3185ef7f4e 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.h
+++ b/drivers/gpu/drm/i915/i915_sw_fence.h
@@ -75,6 +75,11 @@ int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
 				    unsigned long timeout,
 				    gfp_t gfp);
 
+static inline bool i915_sw_fence_signaled(const struct i915_sw_fence *fence)
+{
+	return atomic_read(&fence->pending) <= 0;
+}
+
 static inline bool i915_sw_fence_done(const struct i915_sw_fence *fence)
 {
 	return atomic_read(&fence->pending) < 0;