Fix: Corrected a number of lockings to avoid race conditions

src/auth.c

@@ -197,7 +197,9 @@ void auth_release (auth_t *authenticator) {
     /* cleanup auth thread attached to this auth */
     if (authenticator->running) {
         authenticator->running = 0;
+        thread_mutex_unlock(&authenticator->lock);
         thread_join(authenticator->thread);
+        thread_mutex_lock(&authenticator->lock);
     }
 
     if (authenticator->free)
@@ -389,15 +391,18 @@ static void *auth_run_thread (void *arg)
     auth_t *auth = arg;
 
     ICECAST_LOG_INFO("Authentication thread started");
-    while (auth->running)
-    {
-        /* usually no clients are waiting, so don't bother taking locks */
-        if (auth->head)
-        {
+    while (1) {
+        thread_mutex_lock(&auth->lock);
+
+        if (!auth->running) {
+            thread_mutex_unlock(&auth->lock);
+            break;
+        }
+
+        if (auth->head) {
             auth_client *auth_user;
 
             /* may become NULL before lock taken */
-            thread_mutex_lock (&auth->lock);
             auth_user = (auth_client*)auth->head;
             if (auth_user == NULL)
             {
@@ -415,6 +420,8 @@ static void *auth_run_thread (void *arg)
             __handle_auth_client(auth, auth_user);
 
             continue;
+        } else {
+            thread_mutex_unlock(&auth->lock);
         }
         thread_sleep (150000);
     }

src/event.c

@@ -36,7 +36,9 @@ static thread_type *event_thread = NULL;
 static void event_addref(event_t *event) {
     if (!event)
         return;
+    thread_mutex_lock(&event_lock);
     event->refcount++;
+    thread_mutex_unlock(&event_lock);
 }
 
 static void event_release(event_t *event) {
@@ -44,9 +46,13 @@ static void event_release(event_t *event) {
 
     if (!event)
         return;
+
+    thread_mutex_lock(&event_lock);
     event->refcount--;
-    if (event->refcount)
+    if (event->refcount) {
+        thread_mutex_unlock(&event_lock);
         return;
+    }
 
     for (i = 0; i < (sizeof(event->reglist)/sizeof(*event->reglist)); i++)
         event_registration_release(event->reglist[i]);
@@ -60,6 +66,7 @@ static void event_release(event_t *event) {
     event_release(event->next);
 
     free(event);
+    thread_mutex_unlock(&event_lock);
 }
 
 static void event_push(event_t **event, event_t *next) {
@@ -78,7 +85,7 @@ static void event_push(event_t **event, event_t *next) {
         return;
     }
 
-    event_addref(*event = next);
+    *event = next;
 }
 
 static void event_push_reglist(event_t *event, event_registration_t *reglist) {
@@ -336,6 +343,7 @@ void event_registration_push(event_registration_t **er, event_registration_t *ta
 /* event signaling */
 void event_emit(event_t *event) {
     fastevent_emit(FASTEVENT_TYPE_SLOWEVENT, FASTEVENT_FLAG_NONE, FASTEVENT_DATATYPE_EVENT, event);
+    event_addref(event);
     thread_mutex_lock(&event_lock);
     event_push(&event_queue, event);
     thread_mutex_unlock(&event_lock);

src/slave.c

@@ -72,7 +72,7 @@ static int slave_running = 0;
 static volatile int update_settings = 0;
 static volatile int update_all_mounts = 0;
 static volatile unsigned int max_interval = 0;
-static mutex_t _slave_mutex; // protects update_settings, update_all_mounts, max_interval
+static mutex_t _slave_mutex; // protects slave_running, update_settings, update_all_mounts, max_interval
 
 static inline void relay_config_upstream_free (relay_config_upstream_t *upstream)
 {
@@ -222,9 +222,14 @@ void slave_initialize(void)
 
 void slave_shutdown(void)
 {
-    if (!slave_running)
+    thread_mutex_lock(&_slave_mutex);
+    if (!slave_running) {
+        thread_mutex_unlock(&_slave_mutex);
         return;
+    }
     slave_running = 0;
+    thread_mutex_unlock(&_slave_mutex);
+
     ICECAST_LOG_DEBUG("waiting for slave thread");
     thread_join (_slave_thread_id);
 }
@@ -895,8 +900,12 @@ static void *_slave_thread(void *arg)
         global_unlock();
 
         thread_sleep(1000000);
-        if (slave_running == 0)
+        thread_mutex_lock(&_slave_mutex);
+        if (slave_running == 0) {
+            thread_mutex_unlock(&_slave_mutex);
             break;
+        }
+        thread_mutex_unlock(&_slave_mutex);
 
         ++interval;
 

src/stats.c

@@ -154,7 +154,9 @@ void stats_shutdown(void)
         return;
 
     /* wait for thread to exit */
+    thread_mutex_lock(&_stats_mutex);
     _stats_running = 0;
+    thread_mutex_unlock(&_stats_mutex);
     thread_join(_stats_thread_id);
 
     /* wait for other threads to shut down */
@@ -691,7 +693,14 @@ static void *_stats_thread(void *arg)
     stats_event (NULL, "listener_connections", "0");
 
     ICECAST_LOG_INFO("stats thread started");
-    while (_stats_running) {
+    while (1) {
+        thread_mutex_lock(&_stats_mutex);
+        if (!_stats_running) {
+            thread_mutex_unlock(&_stats_mutex);
+            break;
+        }
+        thread_mutex_unlock(&_stats_mutex);
+
         thread_mutex_lock(&_global_event_mutex);
         if (_global_event_queue.head != NULL) {
             /* grab the next event from the queue */
@@ -971,7 +980,14 @@ void *stats_connection(void *arg)
 
     _register_listener (&listener);
 
-    while (_stats_running) {
+    while (1) {
+        thread_mutex_lock(&_stats_mutex);
+        if (!_stats_running) {
+            thread_mutex_unlock(&_stats_mutex);
+            break;
+        }
+        thread_mutex_unlock(&_stats_mutex);
+
         thread_mutex_lock (&listener.mutex);
         event = _get_event_from_queue (&listener.queue);
         thread_mutex_unlock (&listener.mutex);

src/yp.c

@@ -721,10 +721,12 @@ static void delete_marked_yp(struct yp_server *server)
 static void *yp_update_thread(void *arg)
 {
     ICECAST_LOG_INFO("YP update thread started");
+    int running;
 
     yp_running = 1;
-    while (yp_running)
-    {
+    running = 1;
+
+    while (running) {
         struct yp_server *server;
 
         thread_sleep (200000);
@@ -738,11 +740,10 @@ static void *yp_update_thread(void *arg)
             yp_process_server (server);
             server = server->next;
         }
-        thread_rwlock_unlock (&yp_lock);
-
         /* update the local YP structure */
         if (yp_update)
         {
+            thread_rwlock_unlock(&yp_lock);
             thread_rwlock_wlock (&yp_lock);
             check_servers ();
             server = (struct yp_server *)active_yps;
@@ -754,8 +755,9 @@ static void *yp_update_thread(void *arg)
                 server = server->next;
             }
             yp_update = 0;
-            thread_rwlock_unlock (&yp_lock);
         }
+        running = yp_running;
+        thread_rwlock_unlock(&yp_lock);
     }
     thread_rwlock_destroy (&yp_lock);
     thread_mutex_destroy (&yp_pending_lock);
@@ -984,8 +986,11 @@ void yp_touch (const char *mount)
 
 void yp_shutdown (void)
 {
+    thread_rwlock_wlock(&yp_lock);
     yp_running = 0;
     yp_update = 1;
+    thread_rwlock_unlock(&yp_lock);
+
     if (yp_thread)
         thread_join (yp_thread);
     free ((char*)server_version);