Fix: sessiond: client socket not created by the main thread

The client socket is not created by the session daemon's main thread
which causes calls to umask() to be issued from multiple threads.

Since umask manipulates a process-wide ressource, it should be only be
used by a single thread.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-sessiond/client.c b/src/bin/lttng-sessiond/client.c
index 870277534ec2e1f50dc614b1884f73460f984299..327c1fe1706efabaefdf9dd2a3c5dc7fb4865c3e 100644 (file)
--- a/src/bin/lttng-sessiond/client.c
+++ b/src/bin/lttng-sessiond/client.c
@@ -44,6 +44,7 @@ static bool is_root;
 static struct thread_state {
        sem_t ready;
        bool running;
+       int client_sock;
 } thread_state;
 
 static void set_thread_status(bool running)
@@ -2022,7 +2023,7 @@ static void *thread_manage_clients(void *data)
        uint32_t revents, nb_fd;
        struct command_ctx *cmd_ctx = NULL;
        struct lttng_poll_event events;
-       int client_sock = -1;
+       const int client_sock = thread_state.client_sock;
        struct lttng_pipe *quit_pipe = data;
        const int thread_quit_pipe_fd = lttng_pipe_get_readfd(quit_pipe);
 
@@ -2031,10 +2032,6 @@ static void *thread_manage_clients(void *data)
        is_root = (getuid() == 0);
 
        pthread_cleanup_push(thread_init_cleanup, NULL);
-       client_sock = create_client_sock();
-       if (client_sock < 0) {
-               goto error_listen;
-       }
 
        rcu_register_thread();
 
@@ -2273,11 +2270,9 @@ error:
 error_listen:
 error_create_poll:
        unlink(config.client_unix_sock_path.value);
-       if (client_sock >= 0) {
-               ret = close(client_sock);
-               if (ret) {
-                       PERROR("close");
-               }
+       ret = close(client_sock);
+       if (ret) {
+               PERROR("close");
        }
 
        if (err) {
@@ -2306,7 +2301,8 @@ struct lttng_thread *launch_client_thread(void)
 {
        bool thread_running;
        struct lttng_pipe *client_quit_pipe;
-       struct lttng_thread *thread;
+       struct lttng_thread *thread = NULL;
+       int client_sock_fd = -1;
 
        sem_init(&thread_state.ready, 0, 0);
        client_quit_pipe = lttng_pipe_open(FD_CLOEXEC);
@@ -2314,6 +2310,12 @@ struct lttng_thread *launch_client_thread(void)
                goto error;
        }
 
+       client_sock_fd = create_client_sock();
+       if (client_sock_fd < 0) {
+               goto error;
+       }
+
+       thread_state.client_sock = client_sock_fd;
        thread = lttng_thread_create("Client management",
                        thread_manage_clients,
                        shutdown_client_thread,
@@ -2322,6 +2324,9 @@ struct lttng_thread *launch_client_thread(void)
        if (!thread) {
                goto error;
        }
+       /* The client thread now owns the client sock fd and the quit pipe. */
+       client_sock_fd = -1;
+       client_quit_pipe = NULL;
 
        /*
         * This thread is part of the threads that need to be fully
@@ -2329,11 +2334,16 @@ struct lttng_thread *launch_client_thread(void)
         */
        thread_running = wait_thread_status();
        if (!thread_running) {
-               lttng_thread_put(thread);
-               thread = NULL;
+               goto error;
        }
        return thread;
 error:
+       if (client_sock_fd >= 0) {
+               if (close(client_sock_fd)) {
+                       PERROR("Failed to close client socket");
+               }
+       }
+       lttng_thread_put(thread);
        cleanup_client_thread(client_quit_pipe);
        return NULL;
 }

diff --git a/src/bin/lttng-sessiond/thread.c b/src/bin/lttng-sessiond/thread.c
index c685442ba036e55ec24c413375d5409e50f56daf..ff6c0962f33768390500e7e5da2cedee55311a5f 100644 (file)
--- a/src/bin/lttng-sessiond/thread.c
+++ b/src/bin/lttng-sessiond/thread.c
@@ -140,6 +140,9 @@ bool lttng_thread_get(struct lttng_thread *thread)
 
 void lttng_thread_put(struct lttng_thread *thread)
 {
+       if (!thread) {
+               return;
+       }
        assert(thread->ref.refcount);
        urcu_ref_put(&thread->ref, lttng_thread_release);
 }