diff options
Diffstat (limited to 'monitor/qmp.c')
| -rw-r--r-- | monitor/qmp.c | 32 |
1 files changed, 29 insertions, 3 deletions
diff --git a/monitor/qmp.c b/monitor/qmp.c index dfc2156328..613b74ec74 100644 --- a/monitor/qmp.c +++ b/monitor/qmp.c @@ -33,6 +33,27 @@ #include "qapi/qmp/qlist.h" #include "trace.h" +/* + * qmp_dispatcher_co_busy is used for synchronisation between the + * monitor thread and the main thread to ensure that the dispatcher + * coroutine never gets scheduled a second time when it's already + * scheduled (scheduling the same coroutine twice is forbidden). + * + * It is true if the coroutine is active and processing requests. + * Additional requests may then be pushed onto mon->qmp_requests, + * and @qmp_dispatcher_co_shutdown may be set without further ado. + * @qmp_dispatcher_co_busy must not be woken up in this case. + * + * If false, you also have to set @qmp_dispatcher_co_busy to true and + * wake up @qmp_dispatcher_co after pushing the new requests. + * + * The coroutine will automatically change this variable back to false + * before it yields. Nobody else may set the variable to false. + * + * Access must be atomic for thread safety. + */ +static bool qmp_dispatcher_co_busy = true; + struct QMPRequest { /* Owner of the request */ MonitorQMP *mon; @@ -334,6 +355,13 @@ void coroutine_fn monitor_qmp_dispatcher_co(void *data) qatomic_set(&qmp_dispatcher_co, NULL); } +void qmp_dispatcher_co_wake(void) +{ + if (!qatomic_xchg(&qmp_dispatcher_co_busy, true)) { + aio_co_wake(qmp_dispatcher_co); + } +} + static void handle_qmp_command(void *opaque, QObject *req, Error *err) { MonitorQMP *mon = opaque; @@ -395,9 +423,7 @@ static void handle_qmp_command(void *opaque, QObject *req, Error *err) } /* Kick the dispatcher routine */ - if (!qatomic_xchg(&qmp_dispatcher_co_busy, true)) { - aio_co_wake(qmp_dispatcher_co); - } + qmp_dispatcher_co_wake(); } static void monitor_qmp_read(void *opaque, const uint8_t *buf, int size) |