From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Thu, 3 May 2018 18:35:24 +0000 (-0400)
Subject: Enforce locking assumptions during channel creation
X-Git-Tag: v2.11.0-rc1~248
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=71e0a100af7369c2a56db35af7b864eeb5ca4f48;p=lttng-tools.git

Enforce locking assumptions during channel creation

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

diff --git a/src/bin/lttng-sessiond/session.c b/src/bin/lttng-sessiond/session.c
index 01cdfdc00..16431ca15 100644
--- a/src/bin/lttng-sessiond/session.c
+++ b/src/bin/lttng-sessiond/session.c
@@ -134,6 +134,14 @@ void session_lock_list(void)
 	pthread_mutex_lock(&ltt_session_list.lock);
 }
 
+/*
+ * Try to acquire session list lock
+ */
+int session_trylock_list(void)
+{
+	return pthread_mutex_trylock(&ltt_session_list.lock);
+}
+
 /*
  * Release session list lock
  */
diff --git a/src/bin/lttng-sessiond/session.h b/src/bin/lttng-sessiond/session.h
index 3ace323ba..92e7a11ad 100644
--- a/src/bin/lttng-sessiond/session.h
+++ b/src/bin/lttng-sessiond/session.h
@@ -212,6 +212,7 @@ int session_destroy(struct ltt_session *session);
 
 void session_lock(struct ltt_session *session);
 void session_lock_list(void);
+int session_trylock_list(void);
 void session_unlock(struct ltt_session *session);
 void session_unlock_list(void);
 
diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 8120b6df2..62971067c 100644
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -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,