From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37707) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gHZVL-00031O-5H for qemu-devel@nongnu.org; Tue, 30 Oct 2018 15:16:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gHZVI-0005ri-FY for qemu-devel@nongnu.org; Tue, 30 Oct 2018 15:16:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39711) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gHZVI-0005j4-3a for qemu-devel@nongnu.org; Tue, 30 Oct 2018 15:16:40 -0400 From: Markus Armbruster Date: Tue, 30 Oct 2018 20:16:14 +0100 Message-Id: <20181030191620.32168-3-armbru@redhat.com> In-Reply-To: <20181030191620.32168-1-armbru@redhat.com> References: <20181030191620.32168-1-armbru@redhat.com> Subject: [Qemu-devel] [PULL 2/8] monitor: delay monitor iothread creation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Wolfgang Bumiller From: Wolfgang Bumiller Commit d32749deb615 moved the call to monitor_init_globals() to before os_daemonize(), making it an unsuitable place to spawn the monitor iothread as it won't be inherited over the fork() in os_daemonize(). We now spawn the thread the first time we instantiate a monitor which actually has use_io_thread == true. Instantiation of monitors happens only after os_daemonize(). We still need to create the qmp_dispatcher_bh when not using iothreads, so this now still happens in monitor_init_globals(). Signed-off-by: Wolfgang Bumiller Fixes: d32749deb615 ("monitor: move init global earlier") Message-Id: <20180925081507.11873-3-w.bumiller@proxmox.com> Reviewed-by: Eric Blake Reviewed-by: Peter Xu Tested-by: Peter Xu [This fixes a crash on shutdown with --daemonize] Signed-off-by: Markus Armbruster --- monitor.c | 35 +++++++++++++++++++++-------------- 1 file changed, 21 insertions(+), 14 deletions(-) diff --git a/monitor.c b/monitor.c index 66f149c1dc..d39390c2f2 100644 --- a/monitor.c +++ b/monitor.c @@ -708,9 +708,14 @@ static void monitor_qapi_event_init(void) static void handle_hmp_command(Monitor *mon, const char *cmdline); +static void monitor_iothread_init(void); + static void monitor_data_init(Monitor *mon, bool skip_flush, bool use_io_thread) { + if (use_io_thread && !mon_iothread) { + monitor_iothread_init(); + } memset(mon, 0, sizeof(Monitor)); qemu_mutex_init(&mon->mon_lock); qemu_mutex_init(&mon->qmp.qmp_queue_lock); @@ -4461,15 +4466,6 @@ static AioContext *monitor_get_aio_context(void) static void monitor_iothread_init(void) { mon_iothread = iothread_create("mon_iothread", &error_abort); - - /* - * The dispatcher BH must run in the main loop thread, since we - * have commands assuming that context. It would be nice to get - * rid of those assumptions. - */ - qmp_dispatcher_bh = aio_bh_new(iohandler_get_aio_context(), - monitor_qmp_bh_dispatcher, - NULL); } void monitor_init_globals(void) @@ -4479,7 +4475,15 @@ void monitor_init_globals(void) sortcmdlist(); qemu_mutex_init(&monitor_lock); qemu_mutex_init(&mon_fdsets_lock); - monitor_iothread_init(); + + /* + * The dispatcher BH must run in the main loop thread, since we + * have commands assuming that context. It would be nice to get + * rid of those assumptions. + */ + qmp_dispatcher_bh = aio_bh_new(iohandler_get_aio_context(), + monitor_qmp_bh_dispatcher, + NULL); } /* These functions just adapt the readline interface in a typesafe way. We @@ -4624,7 +4628,9 @@ void monitor_cleanup(void) * we need to unregister from chardev below in * monitor_data_destroy(), and chardev is not thread-safe yet */ - iothread_stop(mon_iothread); + if (mon_iothread) { + iothread_stop(mon_iothread); + } /* Flush output buffers and destroy monitors */ qemu_mutex_lock(&monitor_lock); @@ -4639,9 +4645,10 @@ void monitor_cleanup(void) /* QEMUBHs needs to be deleted before destroying the I/O thread */ qemu_bh_delete(qmp_dispatcher_bh); qmp_dispatcher_bh = NULL; - - iothread_destroy(mon_iothread); - mon_iothread = NULL; + if (mon_iothread) { + iothread_destroy(mon_iothread); + mon_iothread = NULL; + } } QemuOptsList qemu_mon_opts = { -- 2.17.2