When the device disappear, the function hso_disconnect() is called to
perform cleanup. In the cleanup function, hso_free_interface() calls
tty_port_tty_hangup() in view of scheduling a work to hang up the tty if
needed. If the port was not open then hso_serial_ref_free() is called
directly to cleanup everything. Otherwise, hso_serial_ref_free() is called
when the last fd associated to the port is closed.
For each open port, tty_release() will call the close method,
hso_serial_close(), which drops the last kref and call
hso_serial_ref_free() which unregisters, destroys the tty port
and finally frees the structure in which the tty_port structure
is included. Later, in tty_release(), more precisely when release_tty()
is called, the tty_port previously freed is accessed to cancel
the tty buf workqueue and it leads to a crash.
In view of avoiding this crash, we add a cleanup method that is called
at the end of the hangup process and we drop the last kref in this
function when all the ports have been closed, when tty_port is no
more needed and when it is safe to free the structure containing the
tty_port structure.
Signed-off-by: Olivier Sobrie <olivier@xxxxxxxxx>
---
drivers/net/usb/hso.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index cb0bcc1..3a6c630 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -1270,7 +1270,6 @@ static int hso_serial_open(struct tty_struct *tty, struct file *filp)
goto err_out;
D1("Opening %d", serial->minor);
- kref_get(&serial->parent->ref);
/* setup */
tty->driver_data = serial;
@@ -1289,7 +1288,8 @@ static int hso_serial_open(struct tty_struct *tty, struct file *filp)
if (result) {
hso_stop_serial_device(serial->parent);
serial->port.count--;
- kref_put(&serial->parent->ref, hso_serial_ref_free);
+ } else {
+ kref_get(&serial->parent->ref);
}
} else {
D1("Port was already open");
@@ -1339,8 +1339,6 @@ static void hso_serial_close(struct tty_struct *tty, struct file *filp)
usb_autopm_put_interface(serial->parent->interface);
mutex_unlock(&serial->parent->mutex);
-
- kref_put(&serial->parent->ref, hso_serial_ref_free);
}
/* close the requested serial port */
@@ -1391,6 +1389,16 @@ static int hso_serial_write_room(struct tty_struct *tty)
return room;
}
+static void hso_serial_cleanup(struct tty_struct *tty)
+{
+ struct hso_serial *serial = tty->driver_data;
+
+ if (!serial)
+ return;
+
+ kref_put(&serial->parent->ref, hso_serial_ref_free);
+}
+
/* setup the term */
static void hso_serial_set_termios(struct tty_struct *tty, struct ktermios *old)
{
@@ -3215,6 +3223,7 @@ static const struct tty_operations hso_serial_ops = {
.close = hso_serial_close,
.write = hso_serial_write,
.write_room = hso_serial_write_room,
+ .cleanup = hso_serial_cleanup,
.ioctl = hso_serial_ioctl,
.set_termios = hso_serial_set_termios,
.chars_in_buffer = hso_serial_chars_in_buffer,
--
2.2.0
--
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