monitor: introduce qmp_dispatcher_co_wake

This makes it possible to turn qmp_dispatcher_co_busy into a static
variable.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2023-03-03 13:51:44 +01:00
parent 0ff2553701
commit 9f2d58546e
3 changed files with 31 additions and 29 deletions

View file

@ -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)