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From 5235a7f3692a4c3c90dd4ac1be3c670388904bbe Mon Sep 17 00:00:00 2001
From: Tatu Frisk <tatu.frisk@ge.com>
Date: Tue, 14 Mar 2017 14:41:27 +0200
Subject: [PATCH] Fix hanging issue in _XReply
Assume event queue is empty if another thread is blocking waiting for event.
If one thread was blocking waiting for an event and another thread sent a
reply to the X server, both threads got blocked until an event was
received.
Upstream-Status: Backport [93a050c3ad2d2264d3880db3791387b1a9bf2e9e]
Signed-off-by: Ross Burton <ross.burton@arm.com>
---
src/xcb_io.c | 19 +++++++------------
1 file changed, 7 insertions(+), 12 deletions(-)
Index: libX11-1.6.7/src/xcb_io.c
===================================================================
--- libX11-1.6.7.orig/src/xcb_io.c
+++ libX11-1.6.7/src/xcb_io.c
@@ -620,18 +620,14 @@ Status _XReply(Display *dpy, xReply *rep
if(dpy->xcb->event_owner == XlibOwnsEventQueue)
{
xcb_generic_reply_t *event;
- /* If some thread is already waiting for events,
- * it will get the first one. That thread must
- * process that event before we can continue. */
- /* FIXME: That event might be after this reply,
- * and might never even come--or there might be
- * multiple threads trying to get events. */
- while(dpy->xcb->event_waiter)
- { /* need braces around ConditionWait */
- ConditionWait(dpy, dpy->xcb->event_notify);
- }
- while((event = poll_for_event(dpy, True)))
- handle_response(dpy, event, True);
+
+ /* Assume event queue is empty if another thread is blocking
+ * waiting for event. */
+ if(!dpy->xcb->event_waiter)
+ {
+ while((event = poll_for_response(dpy)))
+ handle_response(dpy, event, True);
+ }
}
req->reply_waiter = 0;
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