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authorAlan Cox <alan@linux.intel.com>2009-09-19 13:13:24 -0700
committerLive-CD User <linux@linux.site>2009-09-19 13:13:24 -0700
commit4455e344959a217ffc28de2ab1af87541322b343 (patch)
treeaa7f2a74cad38787e9a910a576fe3736cde2d3a8 /drivers/usb/serial/usb-serial.c
parent9a68e39d4a701fb3be03cae9b462408664ebd205 (diff)
tty: USB can now use the shutdown method for kref based freeing of ports
Signed-off-by: Alan Cox <alan@linux.intel.com> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/serial/usb-serial.c')
-rw-r--r--drivers/usb/serial/usb-serial.c28
1 files changed, 7 insertions, 21 deletions
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 21dd72a5a715..31c7a0939b98 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -316,16 +316,19 @@ static void serial_do_down(struct usb_serial_port *port)
*
* Do the resource freeing and refcount dropping for the port. We must
* be careful about ordering and we must avoid freeing up the console.
+ *
+ * Called when the last tty kref is dropped.
*/
-static void serial_do_free(struct usb_serial_port *port)
+static void serial_do_free(struct tty_struct *tty)
{
+ struct usb_serial_port *port = tty->driver_data;
struct usb_serial *serial;
struct module *owner;
/* The console is magical, do not hang up the console hardware
or there will be tears */
- if (port->console)
+ if (port == NULL || port->console)
return;
serial = port->serial;
@@ -350,30 +353,12 @@ static void serial_close(struct tty_struct *tty, struct file *filp)
dbg("%s - port %d", __func__, port->number);
- /* FIXME:
- This leaves a very narrow race. Really we should do the
- serial_do_free() on tty->shutdown(), but tty->shutdown can
- be called from IRQ context and serial_do_free can sleep.
-
- The right fix is probably to make the tty free (which is rare)
- and thus tty->shutdown() occur via a work queue and simplify all
- the drivers that use it.
- */
- if (tty_hung_up_p(filp)) {
- /* serial_hangup already called serial_down at this point.
- Another user may have already reopened the port but
- serial_do_free is refcounted */
- serial_do_free(port);
- return;
- }
-
if (tty_port_close_start(&port->port, tty, filp) == 0)
return;
-
serial_do_down(port);
tty_port_close_end(&port->port, tty);
tty_port_tty_set(&port->port, NULL);
- serial_do_free(port);
+
}
static void serial_hangup(struct tty_struct *tty)
@@ -1243,6 +1228,7 @@ static const struct tty_operations serial_ops = {
.chars_in_buffer = serial_chars_in_buffer,
.tiocmget = serial_tiocmget,
.tiocmset = serial_tiocmset,
+ .shutdown = serial_do_free,
.proc_fops = &serial_proc_fops,
};