On Tue, 3 Jun 2014 18:39:11 +0200
Paolo Bonzini <pbonz...@redhat.com> wrote:
> Event emission must be protected by a mutex because of access to
> the shared rate-limiting state, and to guard against concurrent
> monitor "hot-plug" by means of human-monitor-command.
>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
Reviewed-by: Luiz Capitulino <lcapitul...@redhat.com>
> ---
> monitor.c | 20 ++++++++++++++++++--
> 1 file changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/monitor.c b/monitor.c
> index ebc66fb..f7a4ccf 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -210,6 +210,9 @@ struct Monitor {
> /* QMP checker flags */
> #define QMP_ACCEPT_UNKNOWNS 1
>
> +/* Protects mon_list, monitor_event_state. */
> +static QemuMutex monitor_lock;
> +
> static QLIST_HEAD(mon_list, Monitor) mon_list;
> static QLIST_HEAD(mon_fdsets, MonFdset) mon_fdsets;
> static int mon_refcount;
> @@ -531,10 +534,11 @@ static const char *monitor_event_names[] = {
> };
> QEMU_BUILD_BUG_ON(ARRAY_SIZE(monitor_event_names) != QEVENT_MAX)
>
> -MonitorEventState monitor_event_state[QEVENT_MAX];
> +static MonitorEventState monitor_event_state[QEVENT_MAX];
>
> /*
> - * Emits the event to every monitor instance
> + * Emits the event to every monitor instance.
> + * Called with monitor_lock held.
> */
> static void
> monitor_protocol_event_emit(MonitorEvent event,
> @@ -571,6 +575,7 @@ monitor_protocol_event_queue(MonitorEvent event,
> now);
>
> /* Rate limit of 0 indicates no throttling */
> + qemu_mutex_lock(&monitor_lock);
> if (!evstate->rate) {
> monitor_protocol_event_emit(event, data);
> evstate->last = now;
> @@ -595,6 +600,7 @@ monitor_protocol_event_queue(MonitorEvent event,
> evstate->last = now;
> }
> }
> + qemu_mutex_unlock(&monitor_lock);
> }
>
>
> @@ -612,12 +618,14 @@ static void monitor_protocol_event_handler(void *opaque)
> evstate->data,
> evstate->last,
> now);
> + qemu_mutex_lock(&monitor_lock);
> if (evstate->data) {
> monitor_protocol_event_emit(evstate->event, evstate->data);
> qobject_decref(evstate->data);
> evstate->data = NULL;
> }
> evstate->last = now;
> + qemu_mutex_unlock(&monitor_lock);
> }
>
>
> @@ -5040,6 +5048,11 @@ static void monitor_readline_flush(void *opaque)
> monitor_flush(opaque);
> }
>
> +static void __attribute__((constructor)) monitor_lock_init(void)
> +{
> + qemu_mutex_init(&monitor_lock);
> +}
> +
> void monitor_init(CharDriverState *chr, int flags)
> {
> static int is_first_init = 1;
> @@ -5077,7 +5090,10 @@ void monitor_init(CharDriverState *chr, int flags)
> monitor_event, mon);
> }
>
> + qemu_mutex_lock(&monitor_lock);
> QLIST_INSERT_HEAD(&mon_list, mon, entry);
> + qemu_mutex_unlock(&monitor_lock);
> +
> if (!default_mon || (flags & MONITOR_IS_DEFAULT))
> default_mon = mon;
> }
