From e3e977d45b0750d7e4b8f9cac4b89e8082235188 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Fri, 9 Mar 2018 16:59:56 +0800 Subject: monitor: let suspend/resume work even with QMPs This patches allows QMP monitors to be suspended/resumed. One thing to mention is that for QMPs that are using IOThreads, we need an explicit kick for the IOThread in case it is sleeping. Meanwhile, we need to take special care on non-interactive HMPs. Currently only gdbserver is using that. For these monitors, we still don't allow suspend/resume operations. Since at it, add traces for the operations. Signed-off-by: Peter Xu Message-Id: <20180309090006.10018-14-peterx@redhat.com> Reviewed-by: Eric Blake Signed-off-by: Eric Blake --- monitor.c | 47 ++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 44 insertions(+), 3 deletions(-) (limited to 'monitor.c') diff --git a/monitor.c b/monitor.c index 00de3c37ab..0dab6a450f 100644 --- a/monitor.c +++ b/monitor.c @@ -250,6 +250,21 @@ static inline bool monitor_is_qmp(const Monitor *mon) return (mon->flags & MONITOR_USE_CONTROL); } +/** + * Whether @mon is using readline? Note: not all HMP monitors use + * readline, e.g., gdbserver has a non-interactive HMP monitor, so + * readline is not used there. + */ +static inline bool monitor_uses_readline(const Monitor *mon) +{ + return mon->flags & MONITOR_USE_READLINE; +} + +static inline bool monitor_is_hmp_non_interactive(const Monitor *mon) +{ + return !monitor_is_qmp(mon) && !monitor_uses_readline(mon); +} + /** * Is the current monitor, if any, a QMP monitor? */ @@ -3949,19 +3964,45 @@ static void monitor_command_cb(void *opaque, const char *cmdline, int monitor_suspend(Monitor *mon) { - if (!mon->rs) + if (monitor_is_hmp_non_interactive(mon)) { return -ENOTTY; + } + atomic_inc(&mon->suspend_cnt); + + if (monitor_is_qmp(mon)) { + /* + * Kick iothread to make sure this takes effect. It'll be + * evaluated again in prepare() of the watch object. + */ + aio_notify(iothread_get_aio_context(mon_global.mon_iothread)); + } + + trace_monitor_suspend(mon, 1); return 0; } void monitor_resume(Monitor *mon) { - if (!mon->rs) + if (monitor_is_hmp_non_interactive(mon)) { return; + } + if (atomic_dec_fetch(&mon->suspend_cnt) == 0) { - readline_show_prompt(mon->rs); + if (monitor_is_qmp(mon)) { + /* + * For QMP monitors that are running in IOThread, let's + * kick the thread in case it's sleeping. + */ + if (mon->use_io_thr) { + aio_notify(iothread_get_aio_context(mon_global.mon_iothread)); + } + } else { + assert(mon->rs); + readline_show_prompt(mon->rs); + } } + trace_monitor_suspend(mon, -1); } static QObject *get_qmp_greeting(Monitor *mon) -- cgit v1.2.1