qmp: Call monitor_set_cur() only in qmp_dispatch()

The correct way to set the current monitor for a coroutine handler will
be different than for a blocking handler, so monitor_set_cur() needs to
be called in qmp_dispatch().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20201005155855.256490-7-kwolf@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

include/qapi/qmp/dispatch.h

@@ -14,6 +14,7 @@
 #ifndef QAPI_QMP_DISPATCH_H
 #define QAPI_QMP_DISPATCH_H
 
+#include "monitor/monitor.h"
 #include "qemu/queue.h"
 
 typedef void (QmpCommandFunc)(QDict *, QObject **, Error **);
@@ -49,7 +50,7 @@ const char *qmp_command_name(const QmpCommand *cmd);
 bool qmp_has_success_response(const QmpCommand *cmd);
 QDict *qmp_error_response(Error *err);
 QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
-                    bool allow_oob);
+                    bool allow_oob, Monitor *cur_mon);
 bool qmp_is_oob(const QDict *dict);
 
 typedef void (*qmp_cmd_callback_fn)(const QmpCommand *cmd, void *opaque);

monitor/qmp.c

@@ -135,16 +135,11 @@ static void monitor_qmp_respond(MonitorQMP *mon, QDict *rsp)
 
 static void monitor_qmp_dispatch(MonitorQMP *mon, QObject *req)
 {
-    Monitor *old_mon;
     QDict *rsp;
     QDict *error;
 
-    old_mon = monitor_set_cur(&mon->common);
-    assert(old_mon == NULL);
-
-    rsp = qmp_dispatch(mon->commands, req, qmp_oob_enabled(mon));
-
-    monitor_set_cur(NULL);
+    rsp = qmp_dispatch(mon->commands, req, qmp_oob_enabled(mon),
+                       &mon->common);
 
     if (mon->commands == &qmp_cap_negotiation_commands) {
         error = qdict_get_qdict(rsp, "error");

qapi/qmp-dispatch.c

@@ -89,7 +89,7 @@ bool qmp_is_oob(const QDict *dict)
 }
 
 QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
-                    bool allow_oob)
+                    bool allow_oob, Monitor *cur_mon)
 {
     Error *err = NULL;
     bool oob;
@@ -152,7 +152,13 @@ QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
         args = qdict_get_qdict(dict, "arguments");
         qobject_ref(args);
     }
+
+    assert(monitor_cur() == NULL);
+    monitor_set_cur(cur_mon);
+
     cmd->fn(args, &ret, &err);
+
+    monitor_set_cur(NULL);
     qobject_unref(args);
     if (err) {
         /* or assert(!ret) after reviewing all handlers: */

qga/main.c

@@ -579,7 +579,7 @@ static void process_event(void *opaque, QObject *obj, Error *err)
     }
 
     g_debug("processing command");
-    rsp = qmp_dispatch(&ga_commands, obj, false);
+    rsp = qmp_dispatch(&ga_commands, obj, false, NULL);
 
 end:
     ret = send_response(s, rsp);

stubs/monitor-core.c

@@ -8,6 +8,11 @@ Monitor *monitor_cur(void)
     return NULL;
 }
 
+Monitor *monitor_set_cur(Monitor *mon)
+{
+    return NULL;
+}
+
 void monitor_init_qmp(Chardev *chr, bool pretty, Error **errp)
 {
 }

tests/test-qmp-cmds.c

@@ -152,7 +152,7 @@ static QObject *do_qmp_dispatch(bool allow_oob, const char *template, ...)
     req = qdict_from_vjsonf_nofail(template, ap);
     va_end(ap);
 
-    resp = qmp_dispatch(&qmp_commands, QOBJECT(req), allow_oob);
+    resp = qmp_dispatch(&qmp_commands, QOBJECT(req), allow_oob, NULL);
     g_assert(resp);
     ret = qdict_get(resp, "return");
     g_assert(ret);
@@ -175,7 +175,7 @@ static void do_qmp_dispatch_error(bool allow_oob, ErrorClass cls,
     req = qdict_from_vjsonf_nofail(template, ap);
     va_end(ap);
 
-    resp = qmp_dispatch(&qmp_commands, QOBJECT(req), allow_oob);
+    resp = qmp_dispatch(&qmp_commands, QOBJECT(req), allow_oob, NULL);
     g_assert(resp);
     error = qdict_get_qdict(resp, "error");
     g_assert(error);
@@ -231,7 +231,7 @@ static void test_dispatch_cmd_success_response(void)
     QDict *resp;
 
     qdict_put_str(req, "execute", "cmd-success-response");
-    resp = qmp_dispatch(&qmp_commands, QOBJECT(req), false);
+    resp = qmp_dispatch(&qmp_commands, QOBJECT(req), false, NULL);
     g_assert_null(resp);
     qobject_unref(req);
 }