From d5979e4a295b782fb44a1dc61fb4e01c47bcdf2c Mon Sep 17 00:00:00 2001
From: David Goulet <dgoulet@efficios.com>
Date: Tue, 25 Jun 2013 12:30:59 -0400
Subject: [PATCH] Fix: destroy default created channel if add-context fails

Fixes #554

Signed-off-by: David Goulet <dgoulet@efficios.com>
---
 src/bin/lttng-sessiond/cmd.c       | 27 +++++++++++++++++++++++++--
 src/bin/lttng-sessiond/trace-ust.c | 17 +++++++++++++++++
 src/bin/lttng-sessiond/trace-ust.h |  8 ++++++++
 3 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 9b7306b79..a23a2b761 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -1076,7 +1076,7 @@ error:
 int cmd_add_context(struct ltt_session *session, int domain,
 		char *channel_name, struct lttng_event_context *ctx, int kwpipe)
 {
-	int ret;
+	int ret, chan_kern_created = 0, chan_ust_created = 0;
 
 	switch (domain) {
 	case LTTNG_DOMAIN_KERNEL:
@@ -1088,6 +1088,7 @@ int cmd_add_context(struct ltt_session *session, int domain,
 			if (ret != LTTNG_OK) {
 				goto error;
 			}
+			chan_kern_created = 1;
 		}
 
 		/* Add kernel context to kernel tracer */
@@ -1118,6 +1119,7 @@ int cmd_add_context(struct ltt_session *session, int domain,
 				goto error;
 			}
 			free(attr);
+			chan_ust_created = 1;
 		}
 
 		ret = context_ust_add(usess, domain, ctx, channel_name);
@@ -1136,9 +1138,30 @@ int cmd_add_context(struct ltt_session *session, int domain,
 		goto error;
 	}
 
-	ret = LTTNG_OK;
+	return LTTNG_OK;
 
 error:
+	if (chan_kern_created) {
+		struct ltt_kernel_channel *kchan =
+			trace_kernel_get_channel_by_name(DEFAULT_CHANNEL_NAME,
+					session->kernel_session);
+		/* Created previously, this should NOT fail. */
+		assert(kchan);
+		kernel_destroy_channel(kchan);
+	}
+
+	if (chan_ust_created) {
+		struct ltt_ust_channel *uchan =
+			trace_ust_find_channel_by_name(
+					session->ust_session->domain_global.channels,
+					DEFAULT_CHANNEL_NAME);
+		/* Created previously, this should NOT fail. */
+		assert(uchan);
+		/* Remove from the channel list of the session. */
+		trace_ust_delete_channel(session->ust_session->domain_global.channels,
+				uchan);
+		trace_ust_destroy_channel(uchan);
+	}
 	return ret;
 }
 
diff --git a/src/bin/lttng-sessiond/trace-ust.c b/src/bin/lttng-sessiond/trace-ust.c
index 51632bad4..2c63ef0b5 100644
--- a/src/bin/lttng-sessiond/trace-ust.c
+++ b/src/bin/lttng-sessiond/trace-ust.c
@@ -571,6 +571,23 @@ void trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 	call_rcu(&channel->node.head, destroy_channel_rcu);
 }
 
+/*
+ * Remove an UST channel from a channel HT.
+ */
+void trace_ust_delete_channel(struct lttng_ht *ht,
+		struct ltt_ust_channel *channel)
+{
+	int ret;
+	struct lttng_ht_iter iter;
+
+	assert(ht);
+	assert(channel);
+
+	iter.iter.node = &channel->node.node;
+	ret = lttng_ht_del(ht, &iter);
+	assert(!ret);
+}
+
 /*
  * Cleanup ust metadata structure.
  */
diff --git a/src/bin/lttng-sessiond/trace-ust.h b/src/bin/lttng-sessiond/trace-ust.h
index b21d8c2a7..dcb45c237 100644
--- a/src/bin/lttng-sessiond/trace-ust.h
+++ b/src/bin/lttng-sessiond/trace-ust.h
@@ -160,6 +160,8 @@ struct ltt_ust_event *trace_ust_create_event(struct lttng_event *ev,
 struct ltt_ust_metadata *trace_ust_create_metadata(char *path);
 struct ltt_ust_context *trace_ust_create_context(
 		struct lttng_event_context *ctx);
+void trace_ust_delete_channel(struct lttng_ht *ht,
+		struct ltt_ust_channel *channel);
 
 /*
  * Destroy functions free() the data structure and remove from linked list if
@@ -241,6 +243,12 @@ static inline struct ltt_ust_event *trace_ust_find_event(struct lttng_ht *ht,
 {
 	return NULL;
 }
+static inline
+void trace_ust_delete_channel(struct lttng_ht *ht,
+		struct ltt_ust_channel *channel)
+{
+	return;
+}
 
 #endif /* HAVE_LIBLTTNG_UST_CTL */
 
-- 
2.34.1