From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 12 Dec 2019 16:34:10 +0000 (-0500)
Subject: sessiond: implement kernel clear session
X-Git-Tag: v2.12.0-rc1~134
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=bca212a28b662f1472ab2672d7de3b7c04bc952c

sessiond: implement kernel clear session

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ie47c128fc951b206c7ae50933395e9ade9d0012d
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/kernel.c b/src/bin/lttng-sessiond/kernel.c
index 93afc9d6f..1f987ef7d 100644
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -1647,3 +1647,83 @@ bool kernel_tracer_is_initialized(void)
 {
 	return kernel_tracer_fd >= 0;
 }
+
+/*
+ *  Clear a kernel session.
+ *
+ * Return LTTNG_OK on success or else an LTTng error code.
+ */
+enum lttng_error_code kernel_clear_session(struct ltt_session *session)
+{
+	int ret;
+	enum lttng_error_code status = LTTNG_OK;
+	struct consumer_socket *socket;
+	struct lttng_ht_iter iter;
+	struct ltt_kernel_session *ksess = session->kernel_session;
+
+	assert(ksess);
+	assert(ksess->consumer);
+
+	DBG("Clear kernel session %s (session %" PRIu64 ")",
+			session->name, session->id);
+
+	rcu_read_lock();
+
+	if (ksess->active) {
+		ERR("Expecting inactive session %s (%" PRIu64 ")", session->name, session->id);
+		status = LTTNG_ERR_FATAL;
+		goto end;
+	}
+
+	/*
+	 * Note that this loop will end after one iteration given that there is
+	 * only one kernel consumer.
+	 */
+	cds_lfht_for_each_entry(ksess->consumer->socks->ht, &iter.iter,
+			socket, node.node) {
+		struct ltt_kernel_channel *chan;
+
+		/* For each channel, ask the consumer to clear it. */
+		cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
+			DBG("Clear kernel channel %" PRIu64 ", session %s",
+					chan->key, session->name);
+			ret = consumer_clear_channel(socket, chan->key);
+			if (ret < 0) {
+				goto error;
+			}
+		}
+
+		if (!ksess->metadata) {
+			/*
+			 * Nothing to do for the metadata.
+			 * This is a snapshot session.
+			 * The metadata is genererated on the fly.
+			 */
+			continue;
+		}
+
+		/*
+		 * Clear the metadata channel.
+		 * Metadata channel is not cleared per se but we still need to
+		 * perform a rotation operation on it behind the scene.
+		 */
+		ret = consumer_clear_channel(socket, ksess->metadata->key);
+		if (ret < 0) {
+			goto error;
+		}
+	}
+
+	goto end;
+error:
+	switch (-ret) {
+	case LTTCOMM_CONSUMERD_RELAYD_CLEAR_DISALLOWED:
+	      status = LTTNG_ERR_CLEAR_RELAY_DISALLOWED;
+	      break;
+	default:
+	      status = LTTNG_ERR_CLEAR_FAIL_CONSUMER;
+	      break;
+	}
+end:
+	rcu_read_unlock();
+	return status;
+}
diff --git a/src/bin/lttng-sessiond/kernel.h b/src/bin/lttng-sessiond/kernel.h
index fe14589b7..16a70124d 100644
--- a/src/bin/lttng-sessiond/kernel.h
+++ b/src/bin/lttng-sessiond/kernel.h
@@ -65,6 +65,7 @@ enum lttng_error_code kernel_snapshot_record(
 		uint64_t nb_packets_per_stream);
 int kernel_syscall_mask(int chan_fd, char **syscall_mask, uint32_t *nr_bits);
 enum lttng_error_code kernel_rotate_session(struct ltt_session *session);
+enum lttng_error_code kernel_clear_session(struct ltt_session *session);
 
 int init_kernel_workarounds(void);
 ssize_t kernel_list_tracker_pids(struct ltt_kernel_session *session,