[Mesa-dev] [mesa-dev, mesa-demos][PATCH] sharedtex_mt: fix rendering thread hang

[Awais Belal]

XNextEvent is a blocking call which locks up the display mutex
this causes the rendering threads to hang when they try call
glXSwapBuffers() as that tries to take the same mutex in
underlying calls through XCopyArea().
So we only go to XNextEvent when it has at least one event
and we wouldn't lock indefinitely.

Signed-off-by: Awais Belal <awais_belal at mentor.com>
---
 src/xdemos/sharedtex_mt.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/xdemos/sharedtex_mt.c b/src/xdemos/sharedtex_mt.c
index a90903a..1d503c4 100644
--- a/src/xdemos/sharedtex_mt.c
+++ b/src/xdemos/sharedtex_mt.c
@@ -420,9 +420,14 @@ Resize(struct window *h, unsigned int width, unsigned int height)
 static void
 EventLoop(void)
 {
+   int i;
+   XEvent event;
    while (1) {
-      int i;
-      XEvent event;
+      /* Do we have an event? */
+      if (XPending(gDpy) == 0) {
+         usleep(10000);
+         continue;
+      }
       XNextEvent(gDpy, &event);
       for (i = 0; i < NumWindows; i++) {
 	 struct window *h = &Windows[i];
-- 
1.9.1