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, 7 deletions

diff --git a/drivers/usb/serial/option.c b/drivers/usb/serial/option.c
index 73f8277f88f2..6b1727e751e3 100644
--- a/drivers/usb/serial/option.c
+++ b/drivers/usb/serial/option.c
@@ -571,14 +571,14 @@ static void option_indat_callback(struct urb *urb)
                 dbg("%s: nonzero status: %d on endpoint %02x.",
                     __func__, status, endpoint);
         } else {
-                tty = port->port.tty;
+                tty = tty_port_tty_get(&port->port);
                 if (urb->actual_length) {
                         tty_buffer_request_room(tty, urb->actual_length);
                         tty_insert_flip_string(tty, data, urb->actual_length);
                         tty_flip_buffer_push(tty);
-                } else {
+                } else 
                         dbg("%s: empty read urb received", __func__);
-                }
+                tty_kref_put(tty);
 
                 /* Resubmit urb so we continue receiving */
                 if (port->port.count && status != -ESHUTDOWN) {
@@ -647,9 +647,13 @@ static void option_instat_callback(struct urb *urb)
                         portdata->dsr_state = ((signals & 0x02) ? 1 : 0);
                         portdata->ri_state = ((signals & 0x08) ? 1 : 0);
 
-                        if (port->port.tty && !C_CLOCAL(port->port.tty) &&
-                                        old_dcd_state && !portdata->dcd_state)
-                                tty_hangup(port->port.tty);
+                        if (old_dcd_state && !portdata->dcd_state) {
+                                struct tty_struct *tty =
+                                                tty_port_tty_get(&port->port);
+                                if (tty && !C_CLOCAL(tty))
+                                        tty_hangup(tty);
+                                tty_kref_put(tty);
+                        }
                 } else {
                         dbg("%s: type %x req %x", __func__,
                                 req_pkt->bRequestType, req_pkt->bRequest);
@@ -793,7 +797,7 @@ static void option_close(struct tty_struct *tty,
                 for (i = 0; i < N_OUT_URB; i++)
                         usb_kill_urb(portdata->out_urbs[i]);
         }
-        port->port.tty = NULL;  /* FIXME */
+        tty_port_tty_set(&port->port, NULL);
 }
 
 /* Helper functions used by option_setup_urbs */