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: Submitted [https://patchwork.freedesktop.org/patch/171458/]

This patch needs to be removed once the corresponding patch has been merged upstream.

https://patchwork.freedesktop.org/patch/171458/

Signed-off-by: Tatu Frisk <tatu.frisk@ge.com>
Signed-off-by: Jose Alarcon <jose.alarcon@ge.com>

[Refreshed for 1.6.7 update]
Signed-off-by: Armin Kuster <akuster808@gmail.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;