drm/i915: stop using seqcount for fence pruning

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

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_wait.c b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
index 26ec6579b7cdfa76c782664ba8bccf88c4ca58ff..fa46a54bcbe706ceed5b5420f783a301c08300c7 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_wait.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
@@ -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;
 
@@ -83,15 +82,12 @@ 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))
-                               reservation_object_add_excl_fence(resv, NULL);
-                       reservation_object_unlock(resv);
-               }
+       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;