diff options
Diffstat (limited to 'libX11')
| -rw-r--r-- | libX11/src/xcb_io.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/libX11/src/xcb_io.c b/libX11/src/xcb_io.c index 13c709f2f..afb0267ca 100644 --- a/libX11/src/xcb_io.c +++ b/libX11/src/xcb_io.c @@ -340,7 +340,15 @@ void _XReadEvents(Display *dpy) dpy->xcb->event_waiter = 1;
UnlockDisplay(dpy);
event = xcb_wait_for_event(dpy->xcb->connection);
- InternalLockDisplay(dpy, /* don't skip user locks */ 0);
+ /* It appears that classic Xlib respected user
+ * locks when waking up after waiting for
+ * events. However, if this thread did not have
+ * any user locks, and another thread takes a
+ * user lock and tries to read events, then we'd
+ * deadlock. So we'll choose to let the thread
+ * that got in first consume events, despite the
+ * later thread's user locks. */
+ InternalLockDisplay(dpy, /* ignore user locks */ 1);
dpy->xcb->event_waiter = 0;
ConditionBroadcast(dpy, dpy->xcb->event_notify);
if(!event)
@@ -531,7 +539,10 @@ Status _XReply(Display *dpy, xReply *rep, int extra, Bool discard) req->reply_waiter = 1;
UnlockDisplay(dpy);
response = xcb_wait_for_reply(c, req->sequence, &error);
- InternalLockDisplay(dpy, /* don't skip user locks */ 0);
+ /* Any user locks on another thread must have been taken
+ * while we slept in xcb_wait_for_reply. Classic Xlib
+ * ignored those user locks in this case, so we do too. */
+ InternalLockDisplay(dpy, /* ignore user locks */ 1);
/* We have the response we're looking for. Now, before
* letting anyone else process this sequence number, we
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