Lock consumer data before fd check during destroy

Also, a consumer state error is added just before update UST
applications on registration.

Fixes #595

Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>

diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index b688a4c09e45f25c3d62bc82b86cc73bcb23fe16..6c6386d2b3b1107255260110175743fa04ccf9bf 100644 (file)
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -727,6 +727,12 @@ static void update_ust_app(int app_sock)
 {
        struct ltt_session *sess, *stmp;
 
+       /* Consumer is in an ERROR state. Stop any application update. */
+       if (uatomic_read(&ust_consumerd_state) == CONSUMER_ERROR) {
+               /* Stop the update process since the consumer is dead. */
+               return;
+       }
+
        /* For all tracing session(s) */
        cds_list_for_each_entry_safe(sess, stmp, &session_list_ptr->head, list) {
                session_lock(sess);
@@ -1135,6 +1141,13 @@ restart_poll:
 
 exit:
 error:
+       /*
+        * We lock here because we are about to close the sockets and some other
+        * thread might be using them so wait before we are exclusive which will
+        * abort all other consumer command by other threads.
+        */
+       pthread_mutex_lock(&consumer_data->lock);
+
        /* Immediately set the consumerd state to stopped */
        if (consumer_data->type == LTTNG_CONSUMER_KERNEL) {
                uatomic_set(&kernel_consumerd_state, CONSUMER_ERROR);
@@ -1166,9 +1179,6 @@ error:
                        PERROR("close");
                }
        }
-       /* Cleanup metadata socket mutex. */
-       pthread_mutex_destroy(consumer_data->metadata_sock.lock);
-       free(consumer_data->metadata_sock.lock);
 
        if (sock >= 0) {
                ret = close(sock);
@@ -1180,6 +1190,10 @@ error:
        unlink(consumer_data->err_unix_sock_path);
        unlink(consumer_data->cmd_unix_sock_path);
        consumer_data->pid = 0;
+       pthread_mutex_unlock(&consumer_data->lock);
+       /* Cleanup metadata socket mutex. */
+       pthread_mutex_destroy(consumer_data->metadata_sock.lock);
+       free(consumer_data->metadata_sock.lock);
 
        lttng_poll_clean(&events);
 error_poll: