From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Sun, 23 Aug 2015 03:14:44 +0000 (-0700)
Subject: Fix: don't chain RCU free
X-Git-Tag: v2.8.0-rc1~426
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=627cbbe733b1d69d381c536243fac777ba04780f;ds=sidebyside

Fix: don't chain RCU free

We only do a single rcu_barrier() on teardown of sessiond. Therefore, if
we chain call_rcu, they may not all be executed before exit.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/trace-ust.c b/src/bin/lttng-sessiond/trace-ust.c
index 9bc0b73d0..b70d63673 100644
--- a/src/bin/lttng-sessiond/trace-ust.c
+++ b/src/bin/lttng-sessiond/trace-ust.c
@@ -952,11 +952,6 @@ static void _trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 
 	DBG2("Trace destroy UST channel %s", channel->name);
 
-	/* Destroying all events of the channel */
-	destroy_events(channel->events);
-	/* Destroying all context of the channel */
-	destroy_contexts(channel->ctx);
-
 	free(channel);
 }
 
@@ -975,6 +970,11 @@ static void destroy_channel_rcu(struct rcu_head *head)
 
 void trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 {
+	/* Destroying all events of the channel */
+	destroy_events(channel->events);
+	/* Destroying all context of the channel */
+	destroy_contexts(channel->ctx);
+
 	call_rcu(&channel->node.head, destroy_channel_rcu);
 }
 
@@ -1000,18 +1000,18 @@ void trace_ust_delete_channel(struct lttng_ht *ht,
  */
 static void destroy_channels(struct lttng_ht *channels)
 {
-	int ret;
 	struct lttng_ht_node_str *node;
 	struct lttng_ht_iter iter;
 
 	assert(channels);
 
 	rcu_read_lock();
-
 	cds_lfht_for_each_entry(channels->ht, &iter.iter, node, node) {
-		ret = lttng_ht_del(channels, &iter);
-		assert(!ret);
-		call_rcu(&node->head, destroy_channel_rcu);
+		struct ltt_ust_channel *chan =
+			caa_container_of(node, struct ltt_ust_channel, node);
+
+		trace_ust_delete_channel(channels, chan);
+		trace_ust_destroy_channel(chan);
 	}
 	rcu_read_unlock();