From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Tue, 26 Feb 2019 03:05:32 +0000 (-0500)
Subject: Fix: release reference to ltt_session on error instead of free()
X-Git-Tag: v2.12.0-rc1~650
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=f4cc5e83435948e64f5c7bce395ca19703da02a3;p=lttng-tools.git

Fix: release reference to ltt_session on error instead of free()

Since ltt_session objects within the session daemon are now
reference counted, it is more appropriate to release a reference
on error rather than calling free() directly in session_create().

The session_release() function also performs additional that can
be needed in some of the error paths of session_create().

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 e7967f45e..5e6488e4f 100644
--- a/src/bin/lttng-sessiond/session.c
+++ b/src/bin/lttng-sessiond/session.c
@@ -444,10 +444,12 @@ void session_release(struct urcu_ref *ref)
 	consumer_output_put(session->consumer);
 	snapshot_destroy(&session->snapshot);
 
-	ASSERT_LOCKED(ltt_session_list.lock);
-	del_session_list(session);
-	del_session_ht(session);
-	pthread_cond_broadcast(&ltt_session_list.removal_cond);
+	if (session->published) {
+		ASSERT_LOCKED(ltt_session_list.lock);
+		del_session_list(session);
+		del_session_ht(session);
+		pthread_cond_broadcast(&ltt_session_list.removal_cond);
+	}
 	free(session);
 }
 
@@ -630,6 +632,7 @@ int session_create(char *name, uid_t uid, gid_t gid)
 	 * by session id.
 	 */
 	add_session_ht(new_session);
+	new_session->published = true;
 	session_unlock_list();
 
 	/*
@@ -643,7 +646,9 @@ int session_create(char *name, uid_t uid, gid_t gid)
 
 error:
 error_asprintf:
-	free(new_session);
+	session_lock_list();
+	session_put(new_session);
+	session_unlock_list();
 
 error_malloc:
 	return ret;
diff --git a/src/bin/lttng-sessiond/session.h b/src/bin/lttng-sessiond/session.h
index ec0302920..6a0da6c16 100644
--- a/src/bin/lttng-sessiond/session.h
+++ b/src/bin/lttng-sessiond/session.h
@@ -81,6 +81,8 @@ struct ltt_session {
 	pthread_mutex_t lock;
 	struct cds_list_head list;
 	uint64_t id;		/* session unique identifier */
+	/* Indicates if the session has been added to the session list and ht.*/
+	bool published;
 	/* Indicates if a destroy command has been applied to this session. */
 	bool destroyed;
 	/* UID/GID of the user owning the session */
diff --git a/src/bin/lttng-sessiond/snapshot.c b/src/bin/lttng-sessiond/snapshot.c
index 447806bf4..c4c3bf1f8 100644
--- a/src/bin/lttng-sessiond/snapshot.c
+++ b/src/bin/lttng-sessiond/snapshot.c
@@ -321,7 +321,9 @@ void snapshot_destroy(struct snapshot *obj)
 	struct lttng_ht_iter iter;
 	struct snapshot_output *output;
 
-	assert(obj);
+	if (!obj->output_ht) {
+		return;
+	}
 
 	rcu_read_lock();
 	cds_lfht_for_each_entry(obj->output_ht->ht, &iter.iter, output,