From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Wed, 30 Mar 2022 13:23:46 +0000 (-0400)
Subject: sessiond: document RCU locking assumption during channel metadata statedump
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=60f1b42d6280b6bd386abb726dca4fd3b31d8491;p=deliverable%2Flttng-tools.git

sessiond: document RCU locking assumption during channel metadata statedump

The rcu read lock must be held by the caller during a call to
ust_metadata_channel_statedump. An assertion and a comment are added.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ia57a140d51470cc43cf62d36c9b4b552e1c17191
---

diff --git a/src/bin/lttng-sessiond/ust-metadata.cpp b/src/bin/lttng-sessiond/ust-metadata.cpp
index 566799efd..5f031a9c4 100644
--- a/src/bin/lttng-sessiond/ust-metadata.cpp
+++ b/src/bin/lttng-sessiond/ust-metadata.cpp
@@ -906,12 +906,16 @@ end:
 
 /*
  * Should be called with session registry mutex held.
+ *
+ * RCU read lock must be held by the caller.
  */
 int ust_metadata_channel_statedump(struct ust_registry_session *session,
 		struct ust_registry_channel *chan)
 {
 	int ret;
 
+	ASSERT_RCU_READ_LOCKED();
+
 	/* Don't dump metadata events */
 	if (chan->chan_id == -1U)
 		return 0;