[Mesa-stable] [PATCH 1/3] glx/dri3: Fix glXWaitForSbcOML() to handle targetSBC==0 correctly.

[Mario Kleiner]

targetSBC == 0 is a special case, which asks the function
to block until all pending OpenGL bufferswap requests have
completed.

Currently the function just falls through for targetSBC == 0,
returning bogus results.

This breaks applications originally written and tested against
DRI2 which also rely on this not regressing under DRI3/Present,
e.g., Neuro-Science software like Psychtoolbox-3.

This patch fixes the problem.

Cc: "10.3 10.4" <mesa-stable at lists.freedesktop.org>
Signed-off-by: Mario Kleiner <mario.kleiner.de at gmail.com>
---
 src/glx/dri3_glx.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/glx/dri3_glx.c b/src/glx/dri3_glx.c
index a9ff73b..b4ac278 100644
--- a/src/glx/dri3_glx.c
+++ b/src/glx/dri3_glx.c
@@ -529,7 +529,8 @@ dri3_wait_for_sbc(__GLXDRIdrawable *pdraw, int64_t target_sbc, int64_t *ust,
 {
    struct dri3_drawable *priv = (struct dri3_drawable *) pdraw;
 
-   while (priv->recv_sbc < target_sbc) {
+   while ((target_sbc != 0 && priv->recv_sbc < target_sbc) ||
+          (target_sbc == 0 && priv->recv_sbc < priv->send_sbc)) {
       if (!dri3_wait_for_event(pdraw))
          return 0;
    }
-- 
1.9.1