tty: usb-serial krefs

Use kref in the USB serial drivers so that we don't free tty structures
from under the URB receive handlers as has historically been the case if
you were unlucky. This also gives us a framework for general tty drivers to
use tty_port objects and refcount.

Contains two err->dev_err changes merged together to fix clashes in the
-next tree.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 8 deletions

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 1ac7e802b4b6..c2ac129557aa 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1808,7 +1808,7 @@ static void ftdi_read_bulk_callback(struct urb *urb)
         if (port->port.count <= 0)
                 return;
 
-        tty = port->port.tty;
+        tty = tty_port_tty_get(&port->port);
         if (!tty) {
                 dbg("%s - bad tty pointer - exiting", __func__);
                 return;
@@ -1817,7 +1817,7 @@ static void ftdi_read_bulk_callback(struct urb *urb)
         priv = usb_get_serial_port_data(port);
         if (!priv) {
                 dbg("%s - bad port private data pointer - exiting", __func__);
-                return;
+                goto out;
         }
 
         if (urb != port->read_urb)
@@ -1827,7 +1827,7 @@ static void ftdi_read_bulk_callback(struct urb *urb)
                 /* This will happen at close every time so it is a dbg not an
                    err */
                 dbg("(this is ok on close) nonzero read bulk status received: %d", status);
-                return;
+                goto out;
         }
 
         /* count data bytes, but not status bytes */
@@ -1838,7 +1838,8 @@ static void ftdi_read_bulk_callback(struct urb *urb)
         spin_unlock_irqrestore(&priv->rx_lock, flags);
 
         ftdi_process_read(&priv->rx_work.work);
-
+out:
+        tty_kref_put(tty);
 } /* ftdi_read_bulk_callback */
 
 
@@ -1863,7 +1864,7 @@ static void ftdi_process_read(struct work_struct *work)
         if (port->port.count <= 0)
                 return;
 
-        tty = port->port.tty;
+        tty = tty_port_tty_get(&port->port);
         if (!tty) {
                 dbg("%s - bad tty pointer - exiting", __func__);
                 return;
@@ -1872,13 +1873,13 @@ static void ftdi_process_read(struct work_struct *work)
         priv = usb_get_serial_port_data(port);
         if (!priv) {
                 dbg("%s - bad port private data pointer - exiting", __func__);
-                return;
+                goto out;
         }
 
         urb = port->read_urb;
         if (!urb) {
                 dbg("%s - bad read_urb pointer - exiting", __func__);
-                return;
+                goto out;
         }
 
         data = urb->transfer_buffer;
@@ -2020,7 +2021,7 @@ static void ftdi_process_read(struct work_struct *work)
                         schedule_delayed_work(&priv->rx_work, 1);
                 else
                         dbg("%s - port is closed", __func__);
-                return;
+                goto out;
         }
 
         /* urb is completely processed */
@@ -2041,6 +2042,8 @@ static void ftdi_process_read(struct work_struct *work)
                         err("%s - failed resubmitting read urb, error %d",
                                                         __func__, result);
         }
+out:
+        tty_kref_put(tty);
 } /* ftdi_process_read */