Fix: kernel tracing: flush after stop
authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Wed, 18 May 2016 18:04:12 +0000 (14:04 -0400)
committerJérémie Galarneau <jeremie.galarneau@efficios.com>
Thu, 19 May 2016 04:02:33 +0000 (00:02 -0400)
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@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
src/bin/lttng-sessiond/cmd.c

index 21422a57deb7c674295f37545ccfba35d1ed2f64..cc26e6dae004baeab4177f3589a0e837e7deba34 100644 (file)
@@ -2447,7 +2447,15 @@ 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) {
@@ -2455,7 +2463,7 @@ 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) {
@@ -2463,14 +2471,6 @@ 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;
        }
 
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