[PATCH v6 06/12] monitor: Make current monitor a per-coroutine property

[Kevin Wolf <kwolf@redhat.com>]

This way, a monitor command handler will still be able to access the
current monitor, but when it yields, all other code code will correctly
get NULL from monitor_cur().

Outside of coroutine context, qemu_coroutine_self() returns the leader
coroutine of the current thread.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/monitor/monitor.h |  2 +-
 monitor/hmp.c             |  4 ++--
 monitor/monitor.c         | 27 +++++++++++++++++++++------
 qapi/qmp-dispatch.c       |  4 ++--
 stubs/monitor-core.c      |  2 +-
 5 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
index 43cc746078..16072e325c 100644
--- a/include/monitor/monitor.h
+++ b/include/monitor/monitor.h
@@ -13,7 +13,7 @@ typedef struct MonitorOptions MonitorOptions;
 extern QemuOptsList qemu_mon_opts;
 
 Monitor *monitor_cur(void);
-void monitor_set_cur(Monitor *mon);
+void monitor_set_cur(Coroutine *co, Monitor *mon);
 bool monitor_cur_is_qmp(void);
 
 void monitor_init_globals(void);
diff --git a/monitor/hmp.c b/monitor/hmp.c
index 79be6f26de..3e73a4c3ce 100644
--- a/monitor/hmp.c
+++ b/monitor/hmp.c
@@ -1082,9 +1082,9 @@ void handle_hmp_command(MonitorHMP *mon, const char *cmdline)
 
     /* old_mon is non-NULL when called from qmp_human_monitor_command() */
     old_mon = monitor_cur();
-    monitor_set_cur(&mon->common);
+    monitor_set_cur(qemu_coroutine_self(), &mon->common);
     cmd->cmd(&mon->common, qdict);
-    monitor_set_cur(old_mon);
+    monitor_set_cur(qemu_coroutine_self(), old_mon);
 
     qobject_unref(qdict);
 }
diff --git a/monitor/monitor.c b/monitor/monitor.c
index 182ba136b4..35003bb486 100644
--- a/monitor/monitor.c
+++ b/monitor/monitor.c
@@ -58,24 +58,38 @@ IOThread *mon_iothread;
 /* Bottom half to dispatch the requests received from I/O thread */
 QEMUBH *qmp_dispatcher_bh;
 
-/* Protects mon_list, monitor_qapi_event_state, monitor_destroyed.  */
+/*
+ * Protects mon_list, monitor_qapi_event_state, coroutine_mon,
+ * monitor_destroyed.
+ */
 QemuMutex monitor_lock;
 static GHashTable *monitor_qapi_event_state;
+static GHashTable *coroutine_mon; /* Maps Coroutine* to Monitor* */
 
 MonitorList mon_list;
 int mon_refcount;
 static bool monitor_destroyed;
 
-static __thread Monitor *cur_monitor;
-
 Monitor *monitor_cur(void)
 {
-    return cur_monitor;
+    Monitor *mon;
+
+    qemu_mutex_lock(&monitor_lock);
+    mon = g_hash_table_lookup(coroutine_mon, qemu_coroutine_self());
+    qemu_mutex_unlock(&monitor_lock);
+
+    return mon;
 }
 
-void monitor_set_cur(Monitor *mon)
+void monitor_set_cur(Coroutine *co, Monitor *mon)
 {
-    cur_monitor = mon;
+    qemu_mutex_lock(&monitor_lock);
+    if (mon) {
+        g_hash_table_replace(coroutine_mon, co, mon);
+    } else {
+        g_hash_table_remove(coroutine_mon, co);
+    }
+    qemu_mutex_unlock(&monitor_lock);
 }
 
 /**
@@ -613,6 +627,7 @@ void monitor_init_globals_core(void)
 {
     monitor_qapi_event_init();
     qemu_mutex_init(&monitor_lock);
+    coroutine_mon = g_hash_table_new(NULL, NULL);
 
     /*
      * The dispatcher BH must run in the main loop thread, since we
diff --git a/qapi/qmp-dispatch.c b/qapi/qmp-dispatch.c
index 2fdbc0fba4..5677ba92ca 100644
--- a/qapi/qmp-dispatch.c
+++ b/qapi/qmp-dispatch.c
@@ -154,11 +154,11 @@ QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
     }
 
     assert(monitor_cur() == NULL);
-    monitor_set_cur(cur_mon);
+    monitor_set_cur(qemu_coroutine_self(), cur_mon);
 
     cmd->fn(args, &ret, &err);
 
-    monitor_set_cur(NULL);
+    monitor_set_cur(qemu_coroutine_self(), NULL);
     qobject_unref(args);
     if (err) {
         /* or assert(!ret) after reviewing all handlers: */
diff --git a/stubs/monitor-core.c b/stubs/monitor-core.c
index e493df1027..635e37a6ba 100644
--- a/stubs/monitor-core.c
+++ b/stubs/monitor-core.c
@@ -8,7 +8,7 @@ Monitor *monitor_cur(void)
     return NULL;
 }
 
-void monitor_set_cur(Monitor *mon)
+void monitor_set_cur(Coroutine *co, Monitor *mon)
 {
 }
 
-- 
2.25.4