From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46600) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eot9K-0004DL-Hr for qemu-devel@nongnu.org; Thu, 22 Feb 2018 10:51:12 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eot9G-0004ad-IT for qemu-devel@nongnu.org; Thu, 22 Feb 2018 10:51:10 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:34950 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eot9G-0004ZN-Ce for qemu-devel@nongnu.org; Thu, 22 Feb 2018 10:51:06 -0500 Date: Thu, 22 Feb 2018 15:50:47 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Message-ID: <20180222155047.GQ9323@redhat.com> Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20180124053957.29145-1-peterx@redhat.com> <20180124053957.29145-10-peterx@redhat.com> <20180221160007.GA21436@stefanha-x1.localdomain> <20180222100119.GH18962@xz-mi> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180222100119.GH18962@xz-mi> Subject: Re: [Qemu-devel] [PATCH v7 09/23] monitor: allow using IO thread for parsing List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Xu Cc: Stefan Hajnoczi , qemu-devel@nongnu.org, Stefan Hajnoczi , Paolo Bonzini , Fam Zheng , Juan Quintela , mdroth@linux.vnet.ibm.com, Eric Blake , Laurent Vivier , Markus Armbruster , marcandre.lureau@redhat.com, "Dr . David Alan Gilbert" On Thu, Feb 22, 2018 at 06:01:19PM +0800, Peter Xu wrote: > On Wed, Feb 21, 2018 at 04:00:07PM +0000, Stefan Hajnoczi wrote: > > On Wed, Jan 24, 2018 at 01:39:43PM +0800, Peter Xu wrote: > > > @@ -4034,12 +4044,29 @@ static void sortcmdlist(void) > > > qsort((void *)info_cmds, array_num, elem_size, compare_mon_cmd); > > > } > > > > > > +static GMainContext *monitor_io_context_get(void) > > > +{ > > > + return iothread_get_g_main_context(mon_global.mon_iothread); > > > +} > > > + > > > +static AioContext *monitor_aio_context_get(void) > > > +{ > > > + return iothread_get_aio_context(mon_global.mon_iothread); > > > +} > > > > Please follow the X_get_Y() naming convention instead of X_Y_get(). For > > example, see qemu_get_aio_context() and iothread_get_aio_context(). > > Sure. > > > > > > @@ -4082,11 +4109,41 @@ void error_vprintf_unless_qmp(const char *fmt, va_list ap) > > > } > > > } > > > > > > +static void monitor_list_append(Monitor *mon) > > > +{ > > > + qemu_mutex_lock(&monitor_lock); > > > + QTAILQ_INSERT_HEAD(&mon_list, mon, entry); > > > + qemu_mutex_unlock(&monitor_lock); > > > +} > > > + > > > +static void monitor_qmp_setup_handlers(void *data) > > > > BH functions are usually declared like this: > > > > static void X_bh(void *opaque) > > > > This way it's immediately clear that this function is invoked as a BH. > > > > I suggest renaming the function to monitor_qmp_setup_handlers_bh(). > > Using 'opaque' instead of 'data' is common, too. > > Sure. > > > > > > @@ -4099,24 +4156,55 @@ void monitor_init(Chardev *chr, int flags) > > > } > > > > > > if (monitor_is_qmp(mon)) { > > > - qemu_chr_fe_set_handlers(&mon->chr, monitor_can_read, monitor_qmp_read, > > > - monitor_qmp_event, NULL, mon, NULL, true); > > > qemu_chr_fe_set_echo(&mon->chr, true); > > > json_message_parser_init(&mon->qmp.parser, handle_qmp_command); > > > + if (mon->use_io_thr) { > > > + /* > > > + * It's possible that we already have an IOWatchPoll > > > + * registered for the Chardev during chardev_init_func(). > > > > When does this happen? > > > > This seems like a hack that breaks when certain -chardev options are > > used. For example, what happens if the chardev is a TCP connection with > > reconnect=5. In that case the socket will be connecting asynchronously > > and we cannot just remove the fd watch. > > > > How does this interact with TCP listen chardevs? It looks like the > > listener socket uses the main loop (see tcp_chr_disconnect()). > > > > I'm worried that the chardev layer isn't thread-safe and you haven't > > added anything to protect it or at least refuse to run in unsafe > > conditions. > > Indeed, I did some more reading and noticed that the TCP typed chardev > is really special. > > Firstly there can be the QIO thread that handles sync connecting when > "reconnect" is setup (I don't really understand why we only need the > threads when reconnect != 0, but anyway, I'll just assume we need the > threads). It's done in qmp_chardev_open_socket(). > > Secondly, TCP can support TLS or TELNET (tcp_chr_new_client() handles > the main logic of it), so there can be actually more than one GSource > created for a single TCP chardev. Meanwhile, the > chr_update_read_handler() calls never handles the re-setup of those > special GSources (TLS/TELNET), only the common GSource of TCP stream > read/write. > > And the whole TCP channel is based on QIO stuff, which means I need to > add non-default context support to QIO stuff too... That's mostly > about qio_channel_add_watch(). I may need to pass in context > information, and switch to GSource for that function instead of the > old tags, just like what I did to chardev in general. Rather than changing qio_channel_add_watch() which affects all callers, just add a qio_channel_add_watch_full() variant which includes GMainContext as an extra arg 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 :|