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-rw-r--r--drivers/tty/pty.c10
-rw-r--r--drivers/tty/tty_buffer.c6
-rw-r--r--include/linux/tty.h4
3 files changed, 19 insertions, 1 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index f882ac81b93a..0e273158edac 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -212,10 +212,16 @@ static int pty_signal(struct tty_struct *tty, int sig)
static void pty_flush_buffer(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
+ struct tty_ldisc *ld;
if (!to)
return;
- /* tty_buffer_flush(to); FIXME */
+
+ ld = tty_ldisc_ref(to);
+ tty_buffer_flush(to, ld);
+ if (ld)
+ tty_ldisc_deref(ld);
+
if (to->packet) {
spin_lock_irq(&tty->ctrl_lock);
tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
@@ -425,6 +431,8 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
tty->port = ports[1];
o_tty->port->itty = o_tty;
+ tty_buffer_set_lock_subclass(o_tty->port);
+
tty_driver_kref_get(driver);
tty->count++;
o_tty->count++;
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 3605103fc1ac..75661641f5fe 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -557,3 +557,9 @@ int tty_buffer_set_limit(struct tty_port *port, int limit)
return 0;
}
EXPORT_SYMBOL_GPL(tty_buffer_set_limit);
+
+/* slave ptys can claim nested buffer lock when handling BRK and INTR */
+void tty_buffer_set_lock_subclass(struct tty_port *port)
+{
+ lockdep_set_subclass(&port->buf.lock, TTY_LOCK_SLAVE);
+}
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 849659908f23..55964b9490dd 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -25,6 +25,9 @@
*
* legacy_mutex - Nested tty locks are necessary for releasing pty pairs.
* The stable lock order is master pty first, then slave pty.
+ * tty_buffer lock - slave ptys can claim nested buffer lock when handling
+ * signal chars. The stable lock order is slave pty, then
+ * master.
*/
enum {
@@ -460,6 +463,7 @@ extern void tty_flush_to_ldisc(struct tty_struct *tty);
extern void tty_buffer_free_all(struct tty_port *port);
extern void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld);
extern void tty_buffer_init(struct tty_port *port);
+extern void tty_buffer_set_lock_subclass(struct tty_port *port);
extern speed_t tty_termios_baud_rate(struct ktermios *termios);
extern speed_t tty_termios_input_baud_rate(struct ktermios *termios);
extern void tty_termios_encode_baud_rate(struct ktermios *termios,