Commit ab7a6902 authored by Chris Wilson's avatar Chris Wilson

drm/i915: Return early for await_start on same timeline

Requests within a timeline are ordered by that timeline, so awaiting for
the start of a request within the timeline is a no-op. This used to work
by falling out of the mutex_trylock() as the signaler and waiter had the
same timeline and not returning an error.

Fixes: 6a79d848 ("drm/i915: Lock signaler timeline while navigating")
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: <stable@vger.kernel.org> # v5.5+
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200305134822.2750496-1-chris@chris-wilson.co.uk
parent 07e9c59d
...@@ -837,8 +837,8 @@ i915_request_await_start(struct i915_request *rq, struct i915_request *signal) ...@@ -837,8 +837,8 @@ i915_request_await_start(struct i915_request *rq, struct i915_request *signal)
struct dma_fence *fence; struct dma_fence *fence;
int err; int err;
GEM_BUG_ON(i915_request_timeline(rq) == if (i915_request_timeline(rq) == rcu_access_pointer(signal->timeline))
rcu_access_pointer(signal->timeline)); return 0;
if (i915_request_started(signal)) if (i915_request_started(signal))
return 0; return 0;
......
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