summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--Documentation/serial/driver6
-rw-r--r--drivers/tty/serial/serial_core.c8
2 files changed, 11 insertions, 3 deletions
diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index ba64e4b892e9..c415b0ef4493 100644
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -59,7 +59,9 @@ The core driver uses the info->tmpbuf_sem lock to prevent multi-threaded
access to the info->tmpbuf bouncebuffer used for port writes.
The port_sem semaphore is used to protect against ports being added/
-removed or reconfigured at inappropriate times.
+removed or reconfigured at inappropriate times. Since v2.6.27, this
+semaphore has been the 'mutex' member of the tty_port struct, and
+commonly referred to as the port mutex (or port->mutex).
uart_ops
@@ -248,7 +250,7 @@ hardware.
Other flags may be used (eg, xon/xoff characters) if your
hardware supports hardware "soft" flow control.
- Locking: none.
+ Locking: caller holds port->mutex
Interrupts: caller dependent.
This call must not sleep
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 9d142972ee2d..e31d56159aee 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -436,7 +436,7 @@ uart_get_divisor(struct uart_port *port, unsigned int baud)
EXPORT_SYMBOL(uart_get_divisor);
-/* FIXME: Consistent locking policy */
+/* Caller holds port mutex */
static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
struct ktermios *old_termios)
{
@@ -1173,11 +1173,15 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd,
break;
case TIOCSSERIAL:
+ down_write(&tty->termios_rwsem);
ret = uart_set_info_user(tty, state, uarg);
+ up_write(&tty->termios_rwsem);
break;
case TIOCSERCONFIG:
+ down_write(&tty->termios_rwsem);
ret = uart_do_autoconfig(tty, state);
+ up_write(&tty->termios_rwsem);
break;
case TIOCSERGWILD: /* obsolete */
@@ -1278,7 +1282,9 @@ static void uart_set_termios(struct tty_struct *tty,
return;
}
+ mutex_lock(&state->port.mutex);
uart_change_speed(tty, state, old_termios);
+ mutex_unlock(&state->port.mutex);
/* reload cflag from termios; port driver may have overriden flags */
cflag = tty->termios.c_cflag;