aboutsummaryrefslogtreecommitdiffstats
path: root/drivers
diff options
context:
space:
mode:
authorAlan Cox <alan@redhat.com>2009-01-02 08:44:04 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-02 13:19:37 -0500
commit4bd43f2c31848d751f63e8753cd2788d48fb5f30 (patch)
treef88e890bbee89421271437761024130e0c831853 /drivers
parent7e94b1d9bffc18dca3b45554d9d118a3ffcc4d1b (diff)
tty: Fix close races in USB serial
USB serial has always had races where the tty port usage count can hit zero during a receive event. The internal locking is a mutex so we can't use that in the IRQ handlers. With krefs we can tackle this differently but we still need to be careful. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/usb/serial/usb-serial.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 794b5ffe4397..aafa684a900f 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -269,15 +269,19 @@ static void serial_close(struct tty_struct *tty, struct file *filp)
269 return; 269 return;
270 } 270 }
271 271
272 --port->port.count; 272 if (port->port.count == 1)
273 if (port->port.count == 0)
274 /* only call the device specific close if this 273 /* only call the device specific close if this
275 * port is being closed by the last owner */ 274 * port is being closed by the last owner. Ensure we do
275 * this before we drop the port count. The call is protected
276 * by the port mutex
277 */
276 port->serial->type->close(tty, port, filp); 278 port->serial->type->close(tty, port, filp);
277 279
278 if (port->port.count == (port->console? 1 : 0)) { 280 if (port->port.count == (port->console ? 2 : 1)) {
279 struct tty_struct *tty = tty_port_tty_get(&port->port); 281 struct tty_struct *tty = tty_port_tty_get(&port->port);
280 if (tty) { 282 if (tty) {
283 /* We must do this before we drop the port count to
284 zero. */
281 if (tty->driver_data) 285 if (tty->driver_data)
282 tty->driver_data = NULL; 286 tty->driver_data = NULL;
283 tty_port_tty_set(&port->port, NULL); 287 tty_port_tty_set(&port->port, NULL);
@@ -285,13 +289,14 @@ static void serial_close(struct tty_struct *tty, struct file *filp)
285 } 289 }
286 } 290 }
287 291
288 if (port->port.count == 0) { 292 if (port->port.count == 1) {
289 mutex_lock(&port->serial->disc_mutex); 293 mutex_lock(&port->serial->disc_mutex);
290 if (!port->serial->disconnected) 294 if (!port->serial->disconnected)
291 usb_autopm_put_interface(port->serial->interface); 295 usb_autopm_put_interface(port->serial->interface);
292 mutex_unlock(&port->serial->disc_mutex); 296 mutex_unlock(&port->serial->disc_mutex);
293 module_put(port->serial->type->driver.owner); 297 module_put(port->serial->type->driver.owner);
294 } 298 }
299 --port->port.count;
295 300
296 mutex_unlock(&port->mutex); 301 mutex_unlock(&port->mutex);
297 usb_serial_put(port->serial); 302 usb_serial_put(port->serial);