[lttng-dev] [PATCH lttng-tools 03/10] Fix: kernel tracing: flush after stop

[Mathieu Desnoyers]

We should flush the last packet after stop, not before. Otherwise, we
may end up with events written immediately after the flush, which
defeats the purpose of flushing.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
---
 src/bin/lttng-sessiond/cmd.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 16d8ba2..d57edcd 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -2437,7 +2437,15 @@ int cmd_stop_trace(struct ltt_session *session)
 	if (ksession && ksession->active) {
 		DBG("Stop kernel tracing");
 
-		/* Flush metadata if exist */
+		ret = kernel_stop_session(ksession);
+		if (ret < 0) {
+			ret = LTTNG_ERR_KERN_STOP_FAIL;
+			goto error;
+		}
+
+		kernel_wait_quiescent(kernel_tracer_fd);
+
+		/* Flush metadata after stopping (if exists) */
 		if (ksession->metadata_stream_fd >= 0) {
 			ret = kernel_metadata_flush_buffer(ksession->metadata_stream_fd);
 			if (ret < 0) {
@@ -2445,7 +2453,7 @@ int cmd_stop_trace(struct ltt_session *session)
 			}
 		}
 
-		/* Flush all buffers before stopping */
+		/* Flush all buffers after stopping */
 		cds_list_for_each_entry(kchan, &ksession->channel_list.head, list) {
 			ret = kernel_flush_buffer(kchan);
 			if (ret < 0) {
@@ -2453,14 +2461,6 @@ int cmd_stop_trace(struct ltt_session *session)
 			}
 		}
 
-		ret = kernel_stop_session(ksession);
-		if (ret < 0) {
-			ret = LTTNG_ERR_KERN_STOP_FAIL;
-			goto error;
-		}
-
-		kernel_wait_quiescent(kernel_tracer_fd);
-
 		ksession->active = 0;
 	}
 
-- 
2.1.4