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/whiteheat.c b/drivers/usb/serial/whiteheat.c
index 62424eec33ec..1093d2eb046a 100644
--- a/drivers/usb/serial/whiteheat.c
+++ b/drivers/usb/serial/whiteheat.c
@@ -949,13 +949,12 @@ static void whiteheat_throttle(struct tty_struct *tty)
 {
         struct usb_serial_port *port = tty->driver_data;
         struct whiteheat_private *info = usb_get_serial_port_data(port);
-        unsigned long flags;
 
         dbg("%s - port %d", __func__, port->number);
 
-        spin_lock_irqsave(&info->lock, flags);
+        spin_lock_irq(&info->lock);
         info->flags |= THROTTLED;
-        spin_unlock_irqrestore(&info->lock, flags);
+        spin_unlock_irq(&info->lock);
 
         return;
 }
@@ -966,14 +965,13 @@ static void whiteheat_unthrottle(struct tty_struct *tty)
         struct usb_serial_port *port = tty->driver_data;
         struct whiteheat_private *info = usb_get_serial_port_data(port);
         int actually_throttled;
-        unsigned long flags;
 
         dbg("%s - port %d", __func__, port->number);
 
-        spin_lock_irqsave(&info->lock, flags);
+        spin_lock_irq(&info->lock);
         actually_throttled = info->flags & ACTUALLY_THROTTLED;
         info->flags &= ~(THROTTLED | ACTUALLY_THROTTLED);
-        spin_unlock_irqrestore(&info->lock, flags);
+        spin_unlock_irq(&info->lock);
 
         if (actually_throttled)
                 rx_data_softint(&info->rx_work);