drm/i915: stop using seqcount for fence pruning (4c2488cf) · Commits · 戴 / test

After waiting for a reservation object use reservation_object_test_signaled_rcu to opportunistically prune the fences on the object. This allows removal of the seqcount handling in the reservation object. Signed-off-by:

Christian König <christian.koenig@amd.com> Reviewed-by:

Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/322032/?series=64786&rev=1

drivers/gpu/drm/i915/gem/i915_gem_wait.c

+5 −9

Original line number	Diff line number	Diff line
		@@ -35,7 +35,6 @@ i915_gem_object_wait_reservation(struct reservation_object *resv,
		unsigned int flags,
		long timeout)
		{
		unsigned int seq = __read_seqcount_begin(&resv->seq);
		struct dma_fence *excl;
		bool prune_fences = false;

		@@ -83,16 +82,13 @@ i915_gem_object_wait_reservation(struct reservation_object *resv,

		/*
		* Opportunistically prune the fences iff we know they have all been
		* signaled and that the reservation object has not been changed (i.e.
		* no new fences have been added).
		* signaled.
		*/
		if (prune_fences && !__read_seqcount_retry(&resv->seq, seq)) {
		if (reservation_object_trylock(resv)) {
		if (!__read_seqcount_retry(&resv->seq, seq))
		if (prune_fences && reservation_object_trylock(resv)) {
		if (reservation_object_test_signaled_rcu(resv, true))
		reservation_object_add_excl_fence(resv, NULL);
		reservation_object_unlock(resv);
		}
		}

		return timeout;
		}

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