Enforce locking assumptions during channel creation

[lttng-tools.git] / src / bin / lttng-sessiond / ust-app.c

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 8f0d898219d98e4aba0dcda13eedd1816ac2b5f0..62971067ce00f9d1b000580b4a7a10b45121d7ac 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -2154,7 +2154,7 @@ error:
  * Returns 0 on success or else a negative code which is either -ENOMEM or
  * -ENOTCONN which is the default code if the ustctl_create_session fails.
  */
-static int create_ust_app_session(struct ltt_ust_session *usess,
+static int find_or_create_ust_app_session(struct ltt_ust_session *usess,
                struct ust_app *app, struct ust_app_session **ua_sess_ptr,
                int *is_created)
 {
@@ -2847,6 +2847,7 @@ error:
  * Create and send to the application the created buffers with per UID buffers.
  *
  * This MUST be called with a RCU read side lock acquired.
+ * The session list lock and the session's lock must be acquired.
  *
  * Return 0 on success else a negative value.
  */
@@ -2939,6 +2940,8 @@ static int create_channel_per_uid(struct ust_app *app,
                session = session_find_by_id(ua_sess->tracing_id);
                assert(session);
 
+               assert(pthread_mutex_trylock(&session->lock));
+               assert(session_trylock_list());
                cmd_ret = notification_thread_command_add_channel(
                                notification_thread_handle, session->name,
                                ua_sess->euid, ua_sess->egid,
@@ -2970,6 +2973,7 @@ error:
  * Create and send to the application the created buffers with per PID buffers.
  *
  * Called with UST app session lock held.
+ * The session list lock and the session's lock must be acquired.
  *
  * Return 0 on success else a negative value.
  */
@@ -3032,6 +3036,9 @@ static int create_channel_per_pid(struct ust_app *app,
        chan_reg->consumer_key = ua_chan->key;
        pthread_mutex_unlock(&registry->lock);
 
+       assert(pthread_mutex_trylock(&session->lock));
+       assert(session_trylock_list());
+
        cmd_ret = notification_thread_command_add_channel(
                        notification_thread_handle, session->name,
                        ua_sess->euid, ua_sess->egid,
@@ -4165,7 +4172,7 @@ int ust_app_create_channel_glb(struct ltt_ust_session *usess,
                 * that if session exist, it will simply return a pointer to the ust
                 * app session.
                 */
-               ret = create_ust_app_session(usess, app, &ua_sess, &created);
+               ret = find_or_create_ust_app_session(usess, app, &ua_sess, &created);
                if (ret < 0) {
                        switch (ret) {
                        case -ENOTCONN:
@@ -5041,7 +5048,7 @@ void ust_app_global_create(struct ltt_ust_session *usess, struct ust_app *app)
        struct ust_app_ctx *ua_ctx;
        int is_created = 0;
 
-       ret = create_ust_app_session(usess, app, &ua_sess, &is_created);
+       ret = find_or_create_ust_app_session(usess, app, &ua_sess, &is_created);
        if (ret < 0) {
                /* Tracer is probably gone or ENOMEM. */
                goto error;