From 5235a7f3692a4c3c90dd4ac1be3c670388904bbe Mon Sep 17 00:00:00 2001 From: Tatu Frisk 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 Signed-off-by: Jose Alarcon [Refreshed for 1.6.7 update] Signed-off-by: Armin Kuster --- 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;