Transports now export their state.

* runtime/transport/transport.h: Added prototype for
  _stp_transport_get_state().
* runtime/transport/relay_v2.c (_stp_transport_get_state): New function.
* runtime/transport/relayfs.c (_stp_transport_get_state): Ditto.
* runtime/transport/ring_buffer.c (_stp_transport_data_fs_init): Sets
  state.
  (_stp_transport_data_fs_start): Ditto.
  (_stp_transport_data_fs_stop): Ditto.
  (_stp_transport_get_state): Returns state.
* runtime/print_new.c (stp_print_flush): Checks transport state before
  trying to flush.

4 files changed, 38 insertions, 14 deletions

diff --git a/runtime/transport/relay_v2.c b/runtime/transport/relay_v2.c
index aa6f7b99..65e9c59b 100644
--- a/runtime/transport/relay_v2.c
+++ b/runtime/transport/relay_v2.c
@@ -38,12 +38,6 @@
 #define STP_RELAY_TIMER_INTERVAL		((HZ + 99) / 100)
 #endif
 
-enum _stp_transport_state {
-	STP_TRANSPORT_STOPPED,
-	STP_TRANSPORT_INITIALIZED,
-	STP_TRANSPORT_RUNNING,
-};
-
 struct _stp_relay_data_type {
 	enum _stp_transport_state transport_state;
 	struct rchan *rchan;
@@ -147,6 +141,11 @@ static void __stp_relay_timer_init(void)
 	smp_mb();
 }
 
+static enum _stp_transport_state _stp_transport_get_state(void)
+{
+	return _stp_relay_data.transport_state;
+}
+
 static void _stp_transport_data_fs_overwrite(int overwrite)
 {
 	_stp_relay_data.overwrite_flag = overwrite;
diff --git a/runtime/transport/relayfs.c b/runtime/transport/relayfs.c
index c557efbc..338b2771 100644
--- a/runtime/transport/relayfs.c
+++ b/runtime/transport/relayfs.c
@@ -23,12 +23,6 @@
 #include <linux/relayfs_fs.h>
 #include <linux/namei.h>
 
-enum _stp_transport_state {
-	STP_TRANSPORT_STOPPED,
-	STP_TRANSPORT_INITIALIZED,
-	STP_TRANSPORT_RUNNING,
-};
-
 struct _stp_relay_data_type {
 	enum _stp_transport_state transport_state;
 	struct rchan *rchan;
@@ -136,6 +130,11 @@ err:
 	return rc;
 }
 
+static enum _stp_transport_state _stp_transport_get_state(void)
+{
+	return _stp_relay_data.transport_state;
+}
+
 static void _stp_transport_data_fs_overwrite(int overwrite)
 {
 	_stp_relay_data.rchan->overwrite = overwrite;
diff --git a/runtime/transport/ring_buffer.c b/runtime/transport/ring_buffer.c
index 418465c2..0b73d4b4 100644
--- a/runtime/transport/ring_buffer.c
+++ b/runtime/transport/ring_buffer.c
@@ -19,6 +19,7 @@ struct _stp_ring_buffer_data {
 };
 
 struct _stp_relay_data_type {
+	enum _stp_transport_state transport_state;
 	struct ring_buffer *rb;
 	struct _stp_ring_buffer_data rb_data;
 	cpumask_var_t trace_reader_cpumask;
@@ -384,6 +385,7 @@ static int _stp_transport_data_fs_init(void)
 	int rc;
 	long cpu;
 
+	_stp_relay_data.transport_state = STP_TRANSPORT_STOPPED;
 	_stp_relay_data.rb = NULL;
 
 	// allocate buffer
@@ -428,17 +430,22 @@ static int _stp_transport_data_fs_init(void)
 	}
 
 	dbug_trans(1, "returning 0...\n");
+	_stp_relay_data.transport_state = STP_TRANSPORT_INITIALIZED;
 	return 0;
 }
 
 static void _stp_transport_data_fs_start(void)
 {
-	/* Do nothing. */
+	if (_stp_relay_data.transport_state == STP_TRANSPORT_INITIALIZED) {
+		_stp_relay_data.transport_state = STP_TRANSPORT_RUNNING;
+	}
 }
 
 static void _stp_transport_data_fs_stop(void)
 {
-	/* Do nothing. */
+	if (_stp_relay_data.transport_state == STP_TRANSPORT_RUNNING) {
+		_stp_relay_data.transport_state = STP_TRANSPORT_STOPPED;
+	}
 }
 
 static void _stp_transport_data_fs_close(void)
@@ -454,6 +461,11 @@ static void _stp_transport_data_fs_close(void)
 	__stp_free_ring_buffer();
 }
 
+static enum _stp_transport_state _stp_transport_get_state(void)
+{
+	return _stp_relay_data.transport_state;
+}
+
 static void _stp_transport_data_fs_overwrite(int overwrite)
 {
 	/* FIXME: Just a place holder for now. */
diff --git a/runtime/transport/transport.h b/runtime/transport/transport.h
index b3d15ef3..871e37b3 100644
--- a/runtime/transport/transport.h
+++ b/runtime/transport/transport.h
@@ -54,11 +54,25 @@ static int _stp_ctl_attached;
 
 static int _stp_bufsize;
 
+
+enum _stp_transport_state {
+	STP_TRANSPORT_STOPPED,
+	STP_TRANSPORT_INITIALIZED,
+	STP_TRANSPORT_RUNNING,
+};
+
 /*
  * All transports must provide the following functions.
  */
 
 /*
+ * _stp_transport_get_state
+ *
+ * This function returns the current transport state.
+ */
+static enum _stp_transport_state _stp_transport_get_state(void);
+
+/*
  * _stp_transport_data_fs_init
  *
  * This function allocates any buffers needed, creates files,