[PATCH v2 tty-next 8/8] n_tty: Trace echo output with separate trace configuration

[Peter Hurley <peter@hurleysoftware.com>]

Add trace support for echo output but leave it separately selectable/
buildable from the base trace support.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/tty/n_tty.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 26ae9d7..bd01d97 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -94,6 +94,13 @@
 # define n_tty_trace(tty, f, args...)	do { } while (0)
 #endif
 
+#undef N_TTY_TRACE_ECHOES
+#ifdef N_TTY_TRACE_ECHOES
+# define n_tty_trace_echoes(tty, f, args...)	_n_tty_trace(tty, f, args)
+#else
+# define n_tty_trace_echoes(tty, f, args...)	do { } while (0)
+#endif
+
 struct n_tty_data {
 	/* producer-published */
 	size_t read_head;
@@ -791,13 +798,18 @@ static size_t __process_echoes(struct tty_struct *tty)
 		}
 	}
 
+	n_tty_trace_echoes(tty, "echoes:%zu,%zu commit:%zu head:%zu\n",
+			   ldata->echo_tail, tail, ldata->echo_commit,
+			   ldata->echo_head);
+
 	/* If the echo buffer is nearly full (so that the possibility exists
 	 * of echo overrun before the next commit), then discard enough
 	 * data at the tail to prevent a subsequent overrun */
 	while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
 
-		n_tty_trace(tty, "discard echoes (%zu - %zu > %d)\n",
-			    ldata->echo_commit, tail, ECHO_DISCARD_WATERMARK);
+		n_tty_trace_echoes(tty, "discard echoes (%zu - %zu > %d)\n",
+				   ldata->echo_commit, tail,
+				   ECHO_DISCARD_WATERMARK);
 
 		if (echo_buf(ldata, tail) == ECHO_OP_START) {
 			if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
-- 
1.8.1.2