[Mesa-dev] [PATCH] llvmpipe: Always return some fence in flush

[Tomasz Figa]

If there is no last fence, due to no rendering happening yet, just
create a new signaled fence and return it, to match the expectations of
the EGL sync fence API.

Fixes random "Could not create sync fence 0x3003" assertion failures from
Skia on Android, coming from the following code:

https://android.googlesource.com/platform/frameworks/base/+/master/libs/hwui/pipeline/skia/SkiaOpenGLPipeline.cpp#427

Reproducible especially with thread count >= 4.

Signed-off-by: Tomasz Figa <tfiga at chromium.org>
---
 src/gallium/drivers/llvmpipe/lp_setup.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/gallium/drivers/llvmpipe/lp_setup.c b/src/gallium/drivers/llvmpipe/lp_setup.c
index b087369473..a6f1b54d69 100644
--- a/src/gallium/drivers/llvmpipe/lp_setup.c
+++ b/src/gallium/drivers/llvmpipe/lp_setup.c
@@ -360,7 +360,13 @@ lp_setup_flush( struct lp_setup_context *setup,
    set_scene_state( setup, SETUP_FLUSHED, reason );
 
    if (fence) {
-      lp_fence_reference((struct lp_fence **)fence, setup->last_fence);
+      struct lp_fence *lp_fence = NULL;
+
+      lp_fence_reference(&lp_fence, setup->last_fence);
+      if (!lp_fence)
+         lp_fence = lp_fence_create(0);
+      lp_fence_reference((struct lp_fence **)fence, lp_fence);
+      lp_fence_reference(&lp_fence, NULL);
    }
 }
 
-- 
2.18.0.865.gffc8e1a3cd6-goog