From c9753f7250f33184a1859088a691291f37161f25 Mon Sep 17 00:00:00 2001
From: Francis Deslauriers <francis.deslauriers@efficios.com>
Date: Mon, 27 Sep 2021 14:01:04 -0400
Subject: [PATCH] Fix: missing RCU read side critical sections
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Based on the comments of the called functions.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ica81b648ce88290c4ca7507fb00a78480457cf01
---
 src/bin/lttng-sessiond/action-executor.cpp | 8 ++++++++
 src/bin/lttng-sessiond/event.cpp           | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/src/bin/lttng-sessiond/action-executor.cpp b/src/bin/lttng-sessiond/action-executor.cpp
index 68c9c71cf..34d3b7130 100644
--- a/src/bin/lttng-sessiond/action-executor.cpp
+++ b/src/bin/lttng-sessiond/action-executor.cpp
@@ -309,6 +309,7 @@ static int action_executor_start_session_handler(
 	}
 
 	session_lock_list();
+	rcu_read_lock();
 	session = session_find_by_id(LTTNG_OPTIONAL_GET(item->context.session_id));
 	if (!session) {
 		DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
@@ -353,6 +354,7 @@ error_unlock_session:
 	session_unlock(session);
 	session_put(session);
 error_unlock_list:
+	rcu_read_unlock();
 	session_unlock_list();
 end:
 	return ret;
@@ -392,6 +394,7 @@ static int action_executor_stop_session_handler(
 	}
 
 	session_lock_list();
+	rcu_read_lock();
 	session = session_find_by_id(LTTNG_OPTIONAL_GET(item->context.session_id));
 	if (!session) {
 		DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
@@ -436,6 +439,7 @@ error_unlock_session:
 	session_unlock(session);
 	session_put(session);
 error_unlock_list:
+	rcu_read_unlock();
 	session_unlock_list();
 end:
 	return ret;
@@ -475,6 +479,7 @@ static int action_executor_rotate_session_handler(
 	}
 
 	session_lock_list();
+	rcu_read_lock();
 	session = session_find_by_id(LTTNG_OPTIONAL_GET(item->context.session_id));
 	if (!session) {
 		DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
@@ -526,6 +531,7 @@ error_unlock_session:
 	session_unlock(session);
 	session_put(session);
 error_unlock_list:
+	rcu_read_unlock();
 	session_unlock_list();
 end:
 	return ret;
@@ -580,6 +586,7 @@ static int action_executor_snapshot_session_handler(
 	}
 
 	session_lock_list();
+	rcu_read_lock();
 	session = session_find_by_id(LTTNG_OPTIONAL_GET(item->context.session_id));
 	if (!session) {
 		DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
@@ -620,6 +627,7 @@ error_unlock_session:
 	session_unlock(session);
 	session_put(session);
 error_unlock_list:
+	rcu_read_unlock();
 	session_unlock_list();
 end:
 	return ret;
diff --git a/src/bin/lttng-sessiond/event.cpp b/src/bin/lttng-sessiond/event.cpp
index d2e4589b2..924df3af1 100644
--- a/src/bin/lttng-sessiond/event.cpp
+++ b/src/bin/lttng-sessiond/event.cpp
@@ -471,6 +471,7 @@ static int agent_enable(struct agent *agt,
 	LTTNG_ASSERT(event);
 	LTTNG_ASSERT(agt);
 
+	rcu_read_lock();
 	aevent = agent_find_event(event->name, event->loglevel_type,
 			event->loglevel, filter_expression, agt);
 	if (!aevent) {
@@ -519,6 +520,7 @@ error:
 		agent_destroy_event(aevent);
 	}
 end:
+	rcu_read_unlock();
 	free(filter);
 	free(filter_expression);
 	return ret;
-- 
2.34.1