[PATCH 1/1] tty BUF DEBUG

[Jiri Slaby]

Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 drivers/tty/pty.c         | 1 +
 drivers/tty/tty_buffer.c  | 1 +
 drivers/tty/tty_io.c      | 4 ++--
 drivers/tty/tty_ldisc.c   | 1 +
 drivers/tty/tty_port.c    | 4 ++--
 drivers/tty/vt/keyboard.c | 2 +-
 6 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 26dcb3b60fb9..644db78bb035 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -445,6 +445,7 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 
 static void pty_cleanup(struct tty_struct *tty)
 {
+	tty->port->itty = ERR_PTR(-2);
 	tty_port_put(tty->port);
 }
 
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index f8eba1c5412f..642a7fc50aa5 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -404,6 +404,7 @@ void tty_schedule_flip(struct tty_port *port)
 	 * flush_to_ldisc() sees buffer data.
 	 */
 	smp_store_release(&buf->tail->commit, buf->tail->used);
+	WARN_RATELIMIT(IS_ERR_OR_NULL(port->itty), "HUH %p\n", port->itty);
 	queue_work(system_unbound_wq, &buf->work);
 }
 EXPORT_SYMBOL(tty_schedule_flip);
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 94cccb6efa32..7dd81d3e0917 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1471,9 +1471,9 @@ static void release_tty(struct tty_struct *tty, int idx)
 		tty->ops->shutdown(tty);
 	tty_free_termios(tty);
 	tty_driver_remove_tty(tty->driver, tty);
-	tty->port->itty = NULL;
+	tty->port->itty = ERR_PTR(-1);
 	if (tty->link)
-		tty->link->port->itty = NULL;
+		tty->link->port->itty = ERR_PTR(-1);
 	tty_buffer_cancel_work(tty->port);
 
 	tty_kref_put(tty->link);
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 84a8ac2a779f..8b2ac1216205 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -615,6 +615,7 @@ int tty_set_ldisc(struct tty_struct *tty, int disc)
 
 	/* Restart the work queue in case no characters kick it off. Safe if
 	   already running */
+	WARN_ON(IS_ERR_OR_NULL(tty->port->itty));
 	tty_buffer_restart_work(tty->port);
 err:
 	tty_ldisc_put(new_ldisc);	/* drop the extra reference */
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 1286f2478bce..70661417dc17 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -27,7 +27,7 @@ static int tty_port_default_receive_buf(struct tty_port *port,
 	struct tty_ldisc *disc;
 
 	tty = READ_ONCE(port->itty);
-	if (!tty)
+	if (IS_ERR_OR_NULL(tty))
 		return 0;
 
 	disc = tty_ldisc_ref(tty);
@@ -253,7 +253,7 @@ static void tty_port_destructor(struct kref *kref)
 	struct tty_port *port = container_of(kref, struct tty_port, kref);
 
 	/* check if last port ref was dropped before tty release */
-	if (WARN_ON(port->itty))
+	if (WARN_ON(!IS_ERR_OR_NULL(port->itty)))
 		return;
 	if (port->xmit_buf)
 		free_page((unsigned long)port->xmit_buf);
diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index f974d6340d04..f0e3e6869908 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -1325,7 +1325,7 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
 
 	tty = vc->port.tty;
 
-	if (tty && (!tty->driver_data)) {
+	if (WARN_ON(tty && (!tty->driver_data))) {
 		/* No driver data? Strange. Okay we fix it then. */
 		tty->driver_data = vc;
 	}
-- 
2.14.3


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