|Summary:||Displays must not be shared across tet_fork|
|Product:||Xtests||Reporter:||Jamey Sharp <jamey>|
|Component:||XTS||Assignee:||Stuart Anderson <anderson>|
|Status:||RESOLVED MOVED||QA Contact:||Xorg testing team <xorg-test>|
|Priority:||high||CC:||aplattner, b.pravin.in, eich, keithp|
|i915 platform:||i915 features:|
Patch to ensure no test shares displays across tet_fork
Don't share displays across tet_fork, and make event test more deterministic
Description Jamey Sharp 2005-09-07 10:44:57 UTC
The XCloseDisplay purpose #6, XGrabDisplay, and XUngrabDisplay tests all open an extra connection and then tet_fork off a new process to do stuff with that connection. After forking these tests also manipulate the extra connection from the parent. Since the Display structure has a lot of state that has to be kept in sync with the server, it isn't reasonable to expect Xlib to deal with having the same Display used in two separate processes. Xlib/XCB has assertions that sanity check the sequence number stream, and that stream is corrupted by this bug in the test suite; the absence of these assertions in the reference implementation of Xlib presumably explains why this bug hasn't been noticed before. All three tests open these extra displays with the XTS function opendisplay, which queues the Display to be closed at the end of the test. That doesn't work since the XCloseDisplay call is made in the parent after the fork. The minimal fix replaces the opendisplay() call with a call to XOpenDisplay(config.display), which means that XCloseDisplay will not be automatically called. It can't be called from the child in any of these cases, because that would make the child hang until the server is ungrabbed; but of course it can't be called from the parent either. For the XGrabServer and XUngrabServer tests I've chosen to let the connection leak, because there's only one test purpose. For XCloseDisplay, I get the file descriptor from the child's Display, and call close(2) on it in the parent after the child exits. This leaks memory but ensures that all connections to the server are closed at the end of the test, so the server can reset. In addition, the XCloseDisplay test uses the "client2" connection in both parent and child as part of the test procedure. The minimal fix for this opens a third connection for use by the child, and allows the parent to continue using client2. I discussed this part of the bug with Keith, who recommended this fix. I have a patch that fixes all three tests.
Comment 1 Jamey Sharp 2005-09-07 10:46:22 UTC
Created attachment 3195 [details] [review] Patch to ensure no test shares displays across tet_fork
Comment 2 Jamey Sharp 2005-09-07 19:28:35 UTC
Created attachment 3199 [details] [review] Don't share displays across tet_fork, and make event test more deterministic This is a minor revision to the previous patch. On Xfake, at least, the XCloseDisplay test appears to succeed only rarely without a couple of extra XSync calls. I'm not sure whether this bug affects the test when the previous patch hasn't been applied, so I'm not opening it as a separate bug.
Comment 3 Egbert Eich 2006-09-21 09:33:46 UTC
Can this be closed? For more references also see: http://lists.x.org/archives/xorg-test/2005-December/000016.html http://lists.x.org/archives/xorg-test/2005-December/000017.html For discussion about the commit: http://lists.x.org/archives/xorg-test/2006-February/000025.html http://lists.x.org/archives/xorg-test/2006-February/000026.html The patches for Xlib10/ungrbsrvr/ungrbsrvr.m and Xlib10/grbsrvr/grbsrvr.m have been committed. For the discussion of a different solution for Xlib3/clsdsply/ clsdsply.m by Geoff Clare see: http://lists.x.org/archives/xorg-test/2006-April/000027.html http://lists.x.org/archives/xorg-test/2006-April/000030.html A slightly modified version of this has been committed to the tree.
Comment 4 Stew Benedict 2008-12-04 06:52:15 UTC
I think this should stay open. We (LSB) are seeing this test still fail, even with the 'Revision 1.3 2006-05-12 10:41:58 gwc' mods referenced in comment 3 on current xcb-based distributions.
Comment 5 Aaron Plattner 2010-08-15 21:50:04 UTC
Created attachment 37892 [details] [review] libxcb fix I posted a patch to the XCB mailing list that should fix this. It's reviewed, but I don't have write access to libxcb so I can't merge it myself. http://lists.freedesktop.org/archives/xcb/2010-August/006364.html
Comment 6 GitLab Migration User 2018-08-10 21:43:18 UTC
-- GitLab Migration Automatic Message -- This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity. You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/xorg/test/xts/issues/8.