15.01.2019, 18:39, "Daniel P. Berrangé" <berra...@redhat.com>: > On Fri, Jan 11, 2019 at 04:36:11PM +0800, Yongji Xie wrote: >> On Fri, 11 Jan 2019 at 16:32, Daniel P. Berrangé <berra...@redhat.com> >> wrote: >> > >> > On Fri, Jan 11, 2019 at 03:50:40PM +0800, Yongji Xie wrote: >> > > On Fri, 11 Jan 2019 at 00:41, Daniel P. Berrangé <berra...@redhat.com> >> wrote: >> > > > >> > > > We need to fix qemu_chr_fe_wait_connected so that it does explicit >> > > > synchronization wrt to any ongoing background connection process. >> > > > It must only return once all TLS/telnet/websock handshakes have >> > > > completed. If we fix that correctly, then I believe it will also >> > > > solve the problem you're trying to address. >> > > > >> > > >> > > Yes, I think this should be the right way to go. To fix it, my thought >> > > is to track the async QIOChannelSocket in SocketChardev. Then we can >> > > easily get the connection progress in qemu_chr_fe_wait_connected(). Do >> > > you have any suggestion? >> > >> > I've got a few patches that refactor the code to fix this. I'll send them >> > today and CC you on them. >> > >> >> That would be great! Thank you. > > It took me rather longer than expected to fully debug all scenarios, but > I've finally sent patches: > > https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg03344.html > > Regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
I didn't do a deep review and may be wrong, but I think the race is still possible in the hotplug case. Example: 1. User adds a chardev (qmp: chardev-add) with 'reconnect' option; 2. Some main-loop iterations... 3. Reconnect timer triggers and starts connection thread; 4. User adds a vhost-user-blk (qmp: device-add): device realize -> wait_connected. Here, there is a chance that we are in the wait_connected and the connection thread is still running. Regards, Yury
