USB: serial: fix assumption that throttle/unthrottle cannot sleep

many serial subdrivers are clearly written as if throttle/unthrottle
cannot sleep. This leads to unneeded atomic submissions. This
patch converts affected drivers in a way to makes very clear that
throttle/unthrottle can sleep. Thus future misdesigns can be avoided
and efficiency and reliability improved.

This removes any such assumption using GFP_KERNEL and spin_lock_irq()

Signed-off-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 6 deletions

diff --git a/drivers/usb/serial/aircable.c b/drivers/usb/serial/aircable.c
index 2cbfab3716e5..b10ac8409411 100644
--- a/drivers/usb/serial/aircable.c
+++ b/drivers/usb/serial/aircable.c
@@ -554,13 +554,12 @@ static void aircable_throttle(struct tty_struct *tty)
 {
         struct usb_serial_port *port = tty->driver_data;
         struct aircable_private *priv = usb_get_serial_port_data(port);
-        unsigned long flags;
 
         dbg("%s - port %d", __func__, port->number);
 
-        spin_lock_irqsave(&priv->rx_lock, flags);
+        spin_lock_irq(&priv->rx_lock);
         priv->rx_flags |= THROTTLED;
-        spin_unlock_irqrestore(&priv->rx_lock, flags);
+        spin_unlock_irq(&priv->rx_lock);
 }
 
 /* Based on ftdi_sio.c unthrottle */
@@ -569,14 +568,13 @@ static void aircable_unthrottle(struct tty_struct *tty)
         struct usb_serial_port *port = tty->driver_data;
         struct aircable_private *priv = usb_get_serial_port_data(port);
         int actually_throttled;
-        unsigned long flags;
 
         dbg("%s - port %d", __func__, port->number);
 
-        spin_lock_irqsave(&priv->rx_lock, flags);
+        spin_lock_irq(&priv->rx_lock);
         actually_throttled = priv->rx_flags & ACTUALLY_THROTTLED;
         priv->rx_flags &= ~(THROTTLED | ACTUALLY_THROTTLED);
-        spin_unlock_irqrestore(&priv->rx_lock, flags);
+        spin_unlock_irq(&priv->rx_lock);
 
         if (actually_throttled)
                 schedule_work(&priv->rx_work);