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, 4 insertions, 32 deletions

diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index 7c4917d77c0a..7b538caec37f 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -216,12 +216,13 @@ static void mos7720_bulk_in_callback(struct urb *urb)
 
         data = urb->transfer_buffer;
 
-        tty = port->port.tty;
+        tty = tty_port_tty_get(&port->port);
         if (tty && 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);
         }
+        tty_kref_put(tty);
 
         if (!port->read_urb) {
                 dbg("URB KILLED !!!");
@@ -262,10 +263,11 @@ static void mos7720_bulk_out_data_callback(struct urb *urb)
 
         dbg("Entering .........");
 
-        tty = mos7720_port->port->port.tty;
+        tty = tty_port_tty_get(&mos7720_port->port->port);
 
         if (tty && mos7720_port->open)
                 tty_wakeup(tty);
+        tty_kref_put(tty);
 }
 
 /*
@@ -1267,29 +1269,6 @@ static int get_lsr_info(struct tty_struct *tty,
         return 0;
 }
 
-/*
- * get_number_bytes_avail - get number of bytes available
- *
- * Purpose: Let user call ioctl to get the count of number of bytes available.
- */
-static int get_number_bytes_avail(struct moschip_port *mos7720_port,
-                                  unsigned int __user *value)
-{
-        unsigned int result = 0;
-        struct tty_struct *tty = mos7720_port->port->port.tty;
-
-        if (!tty)
-                return -ENOIOCTLCMD;
-
-        result = tty->read_cnt;
-
-        dbg("%s(%d) = %d", __func__,  mos7720_port->port->number, result);
-        if (copy_to_user(value, &result, sizeof(int)))
-                return -EFAULT;
-
-        return -ENOIOCTLCMD;
-}
-
 static int set_modem_info(struct moschip_port *mos7720_port, unsigned int cmd,
                           unsigned int __user *value)
 {
@@ -1409,13 +1388,6 @@ static int mos7720_ioctl(struct tty_struct *tty, struct file *file,
         dbg("%s - port %d, cmd = 0x%x", __func__, port->number, cmd);
 
         switch (cmd) {
-        case TIOCINQ:
-                /* return number of bytes available */
-                dbg("%s (%d) TIOCINQ", __func__,  port->number);
-                return get_number_bytes_avail(mos7720_port,
-                                              (unsigned int __user *)arg);
-                break;
-
         case TIOCSERGETLSR:
                 dbg("%s (%d) TIOCSERGETLSR", __func__,  port->number);
                 return get_lsr_info(tty, mos7720_port,