monitor: Clean up fd sets on monitor disconnect

Fd sets are shared by all monitor connections.  Fd sets are considered
to be in use while at least one monitor is connected.  When the last
monitor disconnects, all fds that are members of an fd set with no
outstanding dup references are closed.  This prevents any fd leakage
associated with a client disconnect prior to using a passed fd.

Signed-off-by: Corey Bryant <coreyb@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/monitor.c b/monitor.c
index a4a29b9cd7ff7552e30c3142f972f234df4a0670..ce42466a639a6c9dd226ba60108dfa1ae07dd98a 100644 (file)
--- a/monitor.c
+++ b/monitor.c
@@ -200,6 +200,7 @@ struct Monitor {
 
 static QLIST_HEAD(mon_list, Monitor) mon_list;
 static QLIST_HEAD(mon_fdsets, MonFdset) mon_fdsets;
+static int mon_refcount;
 
 static mon_cmd_t mon_cmds[];
 static mon_cmd_t info_cmds[];
@@ -2391,7 +2392,8 @@ static void monitor_fdset_cleanup(MonFdset *mon_fdset)
     MonFdsetFd *mon_fdset_fd_next;
 
     QLIST_FOREACH_SAFE(mon_fdset_fd, &mon_fdset->fds, next, mon_fdset_fd_next) {
-        if (mon_fdset_fd->removed) {
+        if (mon_fdset_fd->removed ||
+                (QLIST_EMPTY(&mon_fdset->dup_fds) && mon_refcount == 0)) {
             close(mon_fdset_fd->fd);
             g_free(mon_fdset_fd->opaque);
             QLIST_REMOVE(mon_fdset_fd, next);
@@ -2405,6 +2407,16 @@ static void monitor_fdset_cleanup(MonFdset *mon_fdset)
     }
 }
 
+static void monitor_fdsets_cleanup(void)
+{
+    MonFdset *mon_fdset;
+    MonFdset *mon_fdset_next;
+
+    QLIST_FOREACH_SAFE(mon_fdset, &mon_fdsets, next, mon_fdset_next) {
+        monitor_fdset_cleanup(mon_fdset);
+    }
+}
+
 AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id, bool has_opaque,
                       const char *opaque, Error **errp)
 {
@@ -4824,9 +4836,12 @@ static void monitor_control_event(void *opaque, int event)
         data = get_qmp_greeting();
         monitor_json_emitter(mon, data);
         qobject_decref(data);
+        mon_refcount++;
         break;
     case CHR_EVENT_CLOSED:
         json_message_parser_destroy(&mon->mc->parser);
+        mon_refcount--;
+        monitor_fdsets_cleanup();
         break;
     }
 }
@@ -4867,6 +4882,12 @@ static void monitor_event(void *opaque, int event)
             readline_show_prompt(mon->rs);
         }
         mon->reset_seen = 1;
+        mon_refcount++;
+        break;
+
+    case CHR_EVENT_CLOSED:
+        mon_refcount--;
+        monitor_fdsets_cleanup();
         break;
     }
 }