<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN" "http://www.w3.org/TR/REC-html40/strict.dtd"> <html><head><meta name="qrichtext" content="1" /><style type="text/css"> p, li { white-space: pre-wrap; } </style></head><body style=" font-family:'Monospace'; font-size:10pt; font-weight:400; font-style:normal;"> On Wed 15 Jul 2015 13:35:28 Peter Hutterer wrote: > On Mon, Jul 13, 2015 at 05:18:54PM +0100, Barry Scott wrote: > > On Fri 03 Jul 2015 16:14:13 Peter Hutterer wrote: > > > On Thu, Jul 02, 2015 at 04:26:19PM +0100, Barry Scott wrote: > > > > The attached patch works around an issue we hit after we > > > > ported from Fedora 20 to Fedora 21. > > > > > > > > When systemd reboot starts something happens to dbus that > > > > causes Xorg to loop hard using 99% CPU in WaitForSomething. > > > > > > > > The reason for the loop is that the bus_info.fd in dbus-core.c > > > > has been closed. But the expected Disconnected signal is not > > > > received by the messages filter. > > > > > > wouldn't it be better to set up the filter so we get the disconnect > > > signal? > > > > The dbus ping example does not add a filter to see Disconnected. > > https://github.com/sgh/dbus-examples/blob/master/dbus-ping-listen.c > > looking at config/dbus-core.c, there's message_filter which has the handling > for the disconnect signal. and the dbus doc says it's always sent. so the > question is now: did you put printfs into message_filter() to verify that > the signal never arrives? Yes I fully instrumented this code and the related select fd set handling code to root cause the problem. The Disconnect does not arrive is you start a shutdown. > I also notice that message_filter partially shuts down stuff, but it leaves > bus_info.fd in the select set even though as I understand this is closed > now. so it seem the RemoveGeneralSocket() and info->fd = -1; call should go > into message_filter. > > Cheers, > Peter > > > > > The patch works around this issue by removing the fd from the > > > > fd_set that is feed into the Select in WaitForSomething by > > > > calling RemoveGeneralSocket from within wakeup_handler in > > > > dbus-core.c. > > > > > > > > When systemctl is used to stop and restart Xorg outside of the > > > > reboot it works without any problems. > > > > > > > > Barry > > > > > > > > > > > > From ca770dd6e8ebb9a780ce68a07535f976f6120247 Mon Sep 17 00:00:00 2001 > > > > From: Barry Scott <barry.scott@onelan.co.uk> > > > > Date: Tue, 30 Jun 2015 15:58:22 +0100 > > > > Subject: [PATCH] server loops in WaitForSomething when dbus closed by > > > > systemd> > > > > > > > > shutdown > > > > > > > > Work around issue with dbus fd becoming closed by WaitForSomething > > > > still using it in Select. The Select return EBADF but becuase the dbus > > > > fd > > > > is not taken out of the fs_set the code loop forever. > > > > > > > > This state has been seen when systemd starts to shutdown on Fedora 21. > > > > > > > > Signed-off-by: Barry Scott <barry.scott@onelan.co.uk> > > > > --- > > > > > > > > config/dbus-core.c | 13 +++++++++++++ > > > > 1 file changed, 13 insertions(+) > > > > > > > > diff --git a/config/dbus-core.c b/config/dbus-core.c > > > > index 8351ea4..fac8116 100644 > > > > --- a/config/dbus-core.c > > > > +++ b/config/dbus-core.c > > > > @@ -52,6 +52,19 @@ wakeup_handler(void *data, int num_fds, void > > > > *read_mask) > > > > > > > > { > > > > > > > > struct dbus_core_info *info = data; > > > > > > > > + if (info->fd < 0) { > > > > + return; > > > > + } > > > > + > > > > + if (!dbus_connection_get_is_connected(info->connection)) { > > > > + /* must remove the FD here as WaitForSomething's Select will > > > > now > > > > fail + and WaitForSomething will loop hard calling Select. > > > > + The "Disconnected" message has been seen to not arrive. */ > > > > + RemoveGeneralSocket(info->fd); > > > > + info->fd = -1; > > > > + return; > > > > + } > > > > + > > > > > > > > if (info->connection && num_fds > 0 && FD_ISSET(info->fd, (fd_set > > > > *) > > > > read_mask)) {> > > > > > > > > do { > > > > > > > > dbus_connection_read_write_dispatch(info->connection, 0); > > > > > > > > _______________________________________________ > > > > xorg-devel@lists.x.org: X.Org development > > > > Archives: http://lists.x.org/archives/xorg-devel > > > > Info: http://lists.x.org/mailman/listinfo/xorg-devel </body></html>