Commit d622cb58 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Luiz Capitulino
Browse files

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: default avatarLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarLuiz Capitulino <lcapitulino@redhat.com>
parent 6cff3e85

monitor.c

+16 −0
Original line number Diff line number Diff line
@@ -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;

}