sna/gen3+: Flush vertex threads before touching global state

We need to be careful not just when finishing the current vbo to
synchronize with the sharing threads, but also before we emit the batch
state that no other thread will try and do the same.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 11 insertions, 12 deletions

diff --git a/src/sna/gen4_render.c b/src/sna/gen4_render.c
index 829f4e9a..7fc85209 100644
--- a/src/sna/gen4_render.c
+++ b/src/sna/gen4_render.c
@@ -587,6 +587,9 @@ static bool gen4_rectangle_begin(struct sna *sna,
 	int id = op->u.gen4.ve_id;
 	int ndwords;
 
+	if (sna_vertex_wait__locked(&sna->render) && sna->render.vertex_offset)
+		return true;
+
 	/* 7xpipelined pointers + 6xprimitive + 1xflush */
 	ndwords = op->need_magic_ca_pass? 20 : 6;
 	if ((sna->render.vb_id & (1 << id)) == 0)
@@ -606,6 +609,13 @@ static bool gen4_rectangle_begin(struct sna *sna,
 static int gen4_get_rectangles__flush(struct sna *sna,
 				      const struct sna_composite_op *op)
 {
+	/* Preventing discarding new vbo after lock contention */
+	if (sna_vertex_wait__locked(&sna->render)) {
+		int rem = vertex_space(sna);
+		if (rem > op->floats_per_rect)
+			return rem;
+	}
+
 	if (!kgem_check_batch(&sna->kgem, op->need_magic_ca_pass ? 25 : 6))
 		return 0;
 	if (!kgem_check_reloc_and_exec(&sna->kgem, 2))
@@ -621,17 +631,6 @@ static int gen4_get_rectangles__flush(struct sna *sna,
 						     op->u.gen4.wm_kernel);
 	}
 
-	/* Preventing discarding new vbo after lock contention */
-	if (sna->render.active) {
-		int rem;
-
-		sna_vertex_wait__locked(&sna->render);
-
-		rem = vertex_space(sna);
-		if (rem > op->floats_per_rect)
-			return rem;
-	}
-
 	return gen4_vertex_finish(sna);
 }
 
@@ -644,7 +643,7 @@ inline static int gen4_get_rectangles(struct sna *sna,
 
 start:
 	rem = vertex_space(sna);
-	if (rem < op->floats_per_rect) {
+	if (unlikely(rem < op->floats_per_rect)) {
 		DBG(("flushing vbo for %s: %d < %d\n",
 		     __FUNCTION__, rem, op->floats_per_rect));
 		rem = gen4_get_rectangles__flush(sna, op);