sessiond: refactoring: introduce start/stop_kernel_session

[lttng-tools.git] / src / bin / lttng-sessiond / cmd.c

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 7c9477df938787407dc5eaf8b0c569ddfa0557a5..869215b8d920cb7d2a0bd33d22129c34024e199e 100644 (file)
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -1185,6 +1185,7 @@ int cmd_setup_relayd(struct ltt_session *session)
 
        DBG("Setting relayd for session %s", session->name);
 
+       rcu_read_lock();
        if (session->current_trace_chunk) {
                enum lttng_trace_chunk_status status = lttng_trace_chunk_get_id(
                                session->current_trace_chunk, &current_chunk_id.value);
@@ -1198,8 +1199,6 @@ int cmd_setup_relayd(struct ltt_session *session)
                }
        }
 
-       rcu_read_lock();
-
        if (usess && usess->consumer && usess->consumer->type == CONSUMER_DST_NET
                        && usess->consumer->enabled) {
                /* For each consumer socket, send relayd sockets */
@@ -1261,7 +1260,7 @@ error:
 /*
  * Start a kernel session by opening all necessary streams.
  */
-static int start_kernel_session(struct ltt_kernel_session *ksess)
+int start_kernel_session(struct ltt_kernel_session *ksess)
 {
        int ret;
        struct ltt_kernel_channel *kchan;
@@ -1323,6 +1322,53 @@ error:
        return ret;
 }
 
+int stop_kernel_session(struct ltt_kernel_session *ksess)
+{
+       struct ltt_kernel_channel *kchan;
+       bool error_occurred = false;
+       int ret;
+
+       if (!ksess || !ksess->active) {
+               return LTTNG_OK;
+       }
+       DBG("Stopping kernel tracing");
+
+       ret = kernel_stop_session(ksess);
+       if (ret < 0) {
+               ret = LTTNG_ERR_KERN_STOP_FAIL;
+               goto error;
+       }
+
+       kernel_wait_quiescent();
+
+       /* Flush metadata after stopping (if exists) */
+       if (ksess->metadata_stream_fd >= 0) {
+               ret = kernel_metadata_flush_buffer(ksess->metadata_stream_fd);
+               if (ret < 0) {
+                       ERR("Kernel metadata flush failed");
+                       error_occurred = true;
+               }
+       }
+
+       /* Flush all buffers after stopping */
+       cds_list_for_each_entry(kchan, &ksess->channel_list.head, list) {
+               ret = kernel_flush_buffer(kchan);
+               if (ret < 0) {
+                       ERR("Kernel flush buffer error");
+                       error_occurred = true;
+               }
+       }
+
+       ksess->active = 0;
+       if (error_occurred) {
+               ret = LTTNG_ERR_UNK;
+       } else {
+               ret = LTTNG_OK;
+       }
+error:
+       return ret;
+}
+
 /*
  * Command LTTNG_DISABLE_CHANNEL processed by the client thread.
  */
@@ -2717,14 +2763,12 @@ error:
 int cmd_stop_trace(struct ltt_session *session)
 {
        int ret;
-       struct ltt_kernel_channel *kchan;
        struct ltt_kernel_session *ksession;
        struct ltt_ust_session *usess;
-       bool error_occurred = false;
 
        assert(session);
 
-       DBG("Begin stop session %s (id %" PRIu64 ")", session->name, session->id);
+       DBG("Begin stop session \"%s\" (id %" PRIu64 ")", session->name, session->id);
        /* Short cut */
        ksession = session->kernel_session;
        usess = session->ust_session;
@@ -2735,39 +2779,9 @@ int cmd_stop_trace(struct ltt_session *session)
                goto error;
        }
 
-       /* Kernel tracer */
-       if (ksession && ksession->active) {
-               DBG("Stop kernel tracing");
-
-               ret = kernel_stop_session(ksession);
-               if (ret < 0) {
-                       ret = LTTNG_ERR_KERN_STOP_FAIL;
-                       goto error;
-               }
-
-               kernel_wait_quiescent();
-
-               /* Flush metadata after stopping (if exists) */
-               if (ksession->metadata_stream_fd >= 0) {
-                       ret = kernel_metadata_flush_buffer(ksession->metadata_stream_fd);
-                       if (ret < 0) {
-                               ERR("Kernel metadata flush failed");
-                               error_occurred = true;
-                       }
-               }
-
-               /* Flush all buffers after stopping */
-               cds_list_for_each_entry(kchan, &ksession->channel_list.head, list) {
-                       ret = kernel_flush_buffer(kchan);
-                       if (ret < 0) {
-                               ERR("Kernel flush buffer error");
-                               error_occurred = true;
-                       }
-               }
-
-               ksession->active = 0;
-               DBG("Kernel session stopped %s (id %" PRIu64 ")", session->name,
-                               session->id);
+       ret = stop_kernel_session(ksession);
+       if (ret != LTTNG_OK) {
+               goto error;
        }
 
        if (usess && usess->active) {
@@ -2778,9 +2792,11 @@ int cmd_stop_trace(struct ltt_session *session)
                }
        }
 
+       DBG("Completed stop session \"%s\" (id %" PRIu64 ")", session->name,
+                       session->id);
        /* Flag inactive after a successful stop. */
        session->active = 0;
-       ret = !error_occurred ? LTTNG_OK : LTTNG_ERR_UNK;
+       ret = LTTNG_OK;
 
 error:
        return ret;
@@ -4908,6 +4924,12 @@ int cmd_rotate_session(struct ltt_session *session,
                goto end;
        }
 
+       /* Unsupported feature in lttng-modules before 2.8 (lack of sequence number). */
+       if (session->kernel_session && !kernel_supports_ring_buffer_packet_sequence_number()) {
+               cmd_ret = LTTNG_ERR_ROTATION_NOT_AVAILABLE_KERNEL;
+               goto end;
+       }
+
        if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
                DBG("Refusing to launch a rotation; a rotation is already in progress for session %s",
                                session->name);