nouveau: fix fence hang

If there is not enough space in pushbuffer for fence emission
(nouveau_fence_emit -> nv50_screen_fence_emit -> MARK_RING),
the pushbuffer is flushed, which through flush_notify ->
nv50_default_flush_notify -> nouveau_fence_update marks currently
emitting fence as flushed. But actual emission is done after this mark.
So later when there is a need to wait on this fence and pushbuffer
was not flushed in between, fence wait will never finish causing
application to hang.

To fix this, introduce new fence state between AVAILABLE and EMITTED,
set it before emission and handle it everywhere.

Additionally obtain fence sequence numbers after possible flush in
MARK_RING, because we want to emit fences in correct order.

Reviewed-by: Christoph Bumiller <[email protected]>

Note: This is a candidate for the 7.11 branch.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/gallium/drivers/nouveau/nouveau_fence.h b/src/gallium/drivers/nouveau/nouveau_fence.h
index 680c75e99f9..3984a9a942d 100644
--- a/src/gallium/drivers/nouveau/nouveau_fence.h
+++ b/src/gallium/drivers/nouveau/nouveau_fence.h
@@ -6,9 +6,10 @@
 #include "util/u_double_list.h"
 
 #define NOUVEAU_FENCE_STATE_AVAILABLE 0
-#define NOUVEAU_FENCE_STATE_EMITTED   1
-#define NOUVEAU_FENCE_STATE_FLUSHED   2
-#define NOUVEAU_FENCE_STATE_SIGNALLED 3
+#define NOUVEAU_FENCE_STATE_EMITTING  1
+#define NOUVEAU_FENCE_STATE_EMITTED   2
+#define NOUVEAU_FENCE_STATE_FLUSHED   3
+#define NOUVEAU_FENCE_STATE_SIGNALLED 4
 
 struct nouveau_fence_work {
    struct list_head list;