Fix a memory leak that can occur on systems under higher load. The issue is

that when events are appended to the master event queue, they use the number
of active sessions as a use count so it will know when all active sessions
at the time the event happened have consumed it.  However, the handling of
the number of sessions was not properly synchronized, so the use count was
not always correct, causing an event to disappear early, or get stuck in
the event queue for forever.

(closes issue #9238, reported by bweschke, patch from Ivan, modified by me)


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@82867 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/manager.c

@@ -683,9 +683,9 @@ static void destroy_session(struct mansession *s)
 {
 	AST_LIST_LOCK(&sessions);
 	AST_LIST_REMOVE(&sessions, s, list);
+	num_sessions--;
 	AST_LIST_UNLOCK(&sessions);
 
-	ast_atomic_fetchadd_int(&num_sessions, -1);
 	free_session(s);
 }
 
@@ -2235,6 +2235,7 @@ static void *accept_thread(void *ignore)
 		AST_LIST_TRAVERSE_SAFE_BEGIN(&sessions, s, list) {
 			if (s->sessiontimeout && (now > s->sessiontimeout) && !s->inuse) {
 				AST_LIST_REMOVE_CURRENT(&sessions, list);
+				num_sessions--;
 				if (s->authenticated && (option_verbose > 1) && displayconnects) {
 					ast_verbose(VERBOSE_PREFIX_2 "HTTP Manager '%s' timed out from %s\n",
 						s->username, ast_inet_ntoa(s->sin.sin_addr));
@@ -2253,8 +2254,6 @@ static void *accept_thread(void *ignore)
 			free(eqe);
 		}
 		AST_LIST_UNLOCK(&sessions);
-		if (s)
-			ast_atomic_fetchadd_int(&num_sessions, -1);
 
 		sinlen = sizeof(sin);
 		pfds[0].fd = asock;
@@ -2277,8 +2276,6 @@ static void *accept_thread(void *ignore)
 		if (!(s = ast_calloc(1, sizeof(*s))))
 			continue;
 
-		ast_atomic_fetchadd_int(&num_sessions, 1);
-		
 		memcpy(&s->sin, &sin, sizeof(sin));
 		s->writetimeout = 100;
 		s->waiting_thread = AST_PTHREADT_NULL;
@@ -2296,13 +2293,14 @@ static void *accept_thread(void *ignore)
 		s->send_events = -1;
 		AST_LIST_LOCK(&sessions);
 		AST_LIST_INSERT_HEAD(&sessions, s, list);
+		num_sessions++;
 		/* Find the last place in the master event queue and hook ourselves
 		   in there */
 		s->eventq = master_eventq;
 		while(s->eventq->next)
 			s->eventq = s->eventq->next;
-		AST_LIST_UNLOCK(&sessions);
 		ast_atomic_fetchadd_int(&s->eventq->usecount, 1);
+		AST_LIST_UNLOCK(&sessions);
 		if (ast_pthread_create_background(&s->t, &attr, session_do, s))
 			destroy_session(s);
 	}
@@ -2580,9 +2578,9 @@ static char *generic_http_callback(int format, struct sockaddr_in *requestor, co
 		s->eventq = master_eventq;
 		while (s->eventq->next)
 			s->eventq = s->eventq->next;
-		AST_LIST_UNLOCK(&sessions);
 		ast_atomic_fetchadd_int(&s->eventq->usecount, 1);
 		ast_atomic_fetchadd_int(&num_sessions, 1);
+		AST_LIST_UNLOCK(&sessions);
 	}
 
 	/* Reset HTTP timeout.  If we're not yet authenticated, keep it extremely short */