monitor: Use getter/setter functions for cur_mon

cur_mon really needs to be coroutine-local as soon as we move monitor
command handlers to coroutines and let them yield. As a first step, just
remove all direct accesses to cur_mon so that we can implement this in
the getter function later.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20201005155855.256490-4-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>

6 files changed, 40 insertions, 19 deletions

diff --git a/monitor/hmp.c b/monitor/hmp.c
index 4ecdefd705..e0cc9e65dd 100644
--- a/monitor/hmp.c
+++ b/monitor/hmp.c
@@ -1300,12 +1300,11 @@ cleanup:
 
 static void monitor_read(void *opaque, const uint8_t *buf, int size)
 {
-    MonitorHMP *mon;
-    Monitor *old_mon = cur_mon;
+    MonitorHMP *mon = container_of(opaque, MonitorHMP, common);
+    Monitor *old_mon;
     int i;
 
-    cur_mon = opaque;
-    mon = container_of(cur_mon, MonitorHMP, common);
+    old_mon = monitor_set_cur(&mon->common);
 
     if (mon->rs) {
         for (i = 0; i < size; i++) {
@@ -1313,13 +1312,13 @@ static void monitor_read(void *opaque, const uint8_t *buf, int size)
         }
     } else {
         if (size == 0 || buf[size - 1] != 0) {
-            monitor_printf(cur_mon, "corrupted command\n");
+            monitor_printf(&mon->common, "corrupted command\n");
         } else {
             handle_hmp_command(mon, (char *)buf);
         }
     }
 
-    cur_mon = old_mon;
+    monitor_set_cur(old_mon);
 }
 
 static void monitor_event(void *opaque, QEMUChrEvent event)
diff --git a/monitor/misc.c b/monitor/misc.c
index 4ea575eea8..ee8db45094 100644
--- a/monitor/misc.c
+++ b/monitor/misc.c
@@ -125,13 +125,12 @@ char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index,
 
     monitor_data_init(&hmp.common, false, true, false);
 
-    old_mon = cur_mon;
-    cur_mon = &hmp.common;
+    old_mon = monitor_set_cur(&hmp.common);
 
     if (has_cpu_index) {
         int ret = monitor_set_cpu(&hmp.common, cpu_index);
         if (ret < 0) {
-            cur_mon = old_mon;
+            monitor_set_cur(old_mon);
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cpu-index",
                        "a CPU number");
             goto out;
@@ -139,7 +138,7 @@ char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index,
     }
 
     handle_hmp_command(&hmp, command_line);
-    cur_mon = old_mon;
+    monitor_set_cur(old_mon);
 
     WITH_QEMU_LOCK_GUARD(&hmp.common.mon_lock) {
         if (qstring_get_length(hmp.common.outbuf) > 0) {
@@ -297,7 +296,7 @@ static CPUState *mon_get_cpu_sync(Monitor *mon, bool synchronize)
 
 CPUState *mon_get_cpu(void)
 {
-    return mon_get_cpu_sync(cur_mon, true);
+    return mon_get_cpu_sync(monitor_cur(), true);
 }
 
 CPUArchState *mon_get_cpu_env(void)
@@ -1232,6 +1231,7 @@ static void hmp_acl_remove(Monitor *mon, const QDict *qdict)
 
 void qmp_getfd(const char *fdname, Error **errp)
 {
+    Monitor *cur_mon = monitor_cur();
     mon_fd_t *monfd;
     int fd, tmp_fd;
 
@@ -1270,6 +1270,7 @@ void qmp_getfd(const char *fdname, Error **errp)
 
 void qmp_closefd(const char *fdname, Error **errp)
 {
+    Monitor *cur_mon = monitor_cur();
     mon_fd_t *monfd;
     int tmp_fd;
 
@@ -1356,7 +1357,7 @@ AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id, bool has_opaque,
                       const char *opaque, Error **errp)
 {
     int fd;
-    Monitor *mon = cur_mon;
+    Monitor *mon = monitor_cur();
     AddfdInfo *fdinfo;
 
     fd = qemu_chr_fe_get_msgfd(&mon->chr);
diff --git a/monitor/monitor.c b/monitor/monitor.c
index 0f32892ad4..099c164c6d 100644
--- a/monitor/monitor.c
+++ b/monitor/monitor.c
@@ -66,13 +66,31 @@ MonitorList mon_list;
 int mon_refcount;
 static bool monitor_destroyed;
 
-__thread Monitor *cur_mon;
+static __thread Monitor *cur_monitor;
+
+Monitor *monitor_cur(void)
+{
+    return cur_monitor;
+}
+
+/**
+ * Sets a new current monitor and returns the old one.
+ */
+Monitor *monitor_set_cur(Monitor *mon)
+{
+    Monitor *old_monitor = cur_monitor;
+
+    cur_monitor = mon;
+    return old_monitor;
+}
 
 /**
  * Is the current monitor, if any, a QMP monitor?
  */
 bool monitor_cur_is_qmp(void)
 {
+    Monitor *cur_mon = monitor_cur();
+
     return cur_mon && monitor_is_qmp(cur_mon);
 }
 
@@ -209,6 +227,8 @@ int monitor_printf(Monitor *mon, const char *fmt, ...)
  */
 int error_vprintf(const char *fmt, va_list ap)
 {
+    Monitor *cur_mon = monitor_cur();
+
     if (cur_mon && !monitor_cur_is_qmp()) {
         return monitor_vprintf(cur_mon, fmt, ap);
     }
@@ -217,6 +237,8 @@ int error_vprintf(const char *fmt, va_list ap)
 
 int error_vprintf_unless_qmp(const char *fmt, va_list ap)
 {
+    Monitor *cur_mon = monitor_cur();
+
     if (!cur_mon) {
         return vfprintf(stderr, fmt, ap);
     }
diff --git a/monitor/qmp-cmds-control.c b/monitor/qmp-cmds-control.c
index 8f04cfa6e6..a456762f6a 100644
--- a/monitor/qmp-cmds-control.c
+++ b/monitor/qmp-cmds-control.c
@@ -69,6 +69,7 @@ static bool qmp_caps_accept(MonitorQMP *mon, QMPCapabilityList *list,
 void qmp_qmp_capabilities(bool has_enable, QMPCapabilityList *enable,
                           Error **errp)
 {
+    Monitor *cur_mon = monitor_cur();
     MonitorQMP *mon;
 
     assert(monitor_is_qmp(cur_mon));
@@ -119,6 +120,7 @@ static void query_commands_cb(const QmpCommand *cmd, void *opaque)
 CommandInfoList *qmp_query_commands(Error **errp)
 {
     CommandInfoList *list = NULL;
+    Monitor *cur_mon = monitor_cur();
     MonitorQMP *mon;
 
     assert(monitor_is_qmp(cur_mon));
diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
index 0ab5b78580..1abef70a89 100644
--- a/monitor/qmp-cmds.c
+++ b/monitor/qmp-cmds.c
@@ -328,7 +328,7 @@ void qmp_add_client(const char *protocol, const char *fdname,
     Chardev *s;
     int fd;
 
-    fd = monitor_get_fd(cur_mon, fdname, errp);
+    fd = monitor_get_fd(monitor_cur(), fdname, errp);
     if (fd < 0) {
         return;
     }
diff --git a/monitor/qmp.c b/monitor/qmp.c
index d433ceae5b..bb2d9d0cc7 100644
--- a/monitor/qmp.c
+++ b/monitor/qmp.c
@@ -139,12 +139,9 @@ static void monitor_qmp_dispatch(MonitorQMP *mon, QObject *req)
     QDict *rsp;
     QDict *error;
 
-    old_mon = cur_mon;
-    cur_mon = &mon->common;
-
+    old_mon = monitor_set_cur(&mon->common);
     rsp = qmp_dispatch(mon->commands, req, qmp_oob_enabled(mon));
-
-    cur_mon = old_mon;
+    monitor_set_cur(old_mon);
 
     if (mon->commands == &qmp_cap_negotiation_commands) {
         error = qdict_get_qdict(rsp, "error");