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monitor: protect event emission 

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.

Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
This commit is contained in:
Paolo Bonzini 2014-06-18 08:44:00 +02:00 committed by Luiz Capitulino
parent 6cff3e8594
commit d622cb5879
1 changed files with 16 additions and 0 deletions
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16
monitor.c
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@ -217,6 +217,9 @@ 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;
@ -465,6 +468,7 @@ static MonitorQAPIEventState monitor_qapi_event_state[QAPI_EVENT_MAX];
/*
* Emits the event to every monitor instance, @event is only used for trace
* Called with monitor_lock held.
*/
static void monitor_qapi_event_emit(QAPIEvent event, QObject *data)
{
@ -497,6 +501,7 @@ monitor_qapi_event_queue(QAPIEvent event, QDict *data, Error **errp)
now);
/* Rate limit of 0 indicates no throttling */
qemu_mutex_lock(&monitor_lock);
if (!evstate->rate) {
monitor_qapi_event_emit(event, QOBJECT(data));
evstate->last = now;
@ -521,6 +526,7 @@ monitor_qapi_event_queue(QAPIEvent event, QDict *data, Error **errp)
evstate->last = now;
}
}
qemu_mutex_unlock(&monitor_lock);
}
/*
@ -536,12 +542,14 @@ static void monitor_qapi_event_handler(void *opaque)
evstate->data,
evstate->last,
now);
qemu_mutex_lock(&monitor_lock);
if (evstate->data) {
monitor_qapi_event_emit(evstate->event, evstate->data);
qobject_decref(evstate->data);
evstate->data = NULL;
}
evstate->last = now;
qemu_mutex_unlock(&monitor_lock);
}
/*
@ -5292,6 +5300,11 @@ 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;
@ -5329,7 +5342,10 @@ 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;
}