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, 5 insertions, 7 deletions

diff --git a/drivers/usb/serial/garmin_gps.c b/drivers/usb/serial/garmin_gps.c
index 20432d345529..5ac900e5a50e 100644
--- a/drivers/usb/serial/garmin_gps.c
+++ b/drivers/usb/serial/garmin_gps.c
@@ -1390,14 +1390,13 @@ static void garmin_throttle(struct tty_struct *tty)
 {
         struct usb_serial_port *port = tty->driver_data;
         struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
-        unsigned long flags;
 
         dbg("%s - port %d", __func__, port->number);
         /* set flag, data received will be put into a queue
            for later processing */
-        spin_lock_irqsave(&garmin_data_p->lock, flags);
+        spin_lock_irq(&garmin_data_p->lock);
         garmin_data_p->flags |= FLAGS_QUEUING|FLAGS_THROTTLED;
-        spin_unlock_irqrestore(&garmin_data_p->lock, flags);
+        spin_unlock_irq(&garmin_data_p->lock);
 }
 
 
@@ -1405,13 +1404,12 @@ static void garmin_unthrottle(struct tty_struct *tty)
 {
         struct usb_serial_port *port = tty->driver_data;
         struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
-        unsigned long flags;
         int status;
 
         dbg("%s - port %d", __func__, port->number);
-        spin_lock_irqsave(&garmin_data_p->lock, flags);
+        spin_lock_irq(&garmin_data_p->lock);
         garmin_data_p->flags &= ~FLAGS_THROTTLED;
-        spin_unlock_irqrestore(&garmin_data_p->lock, flags);
+        spin_unlock_irq(&garmin_data_p->lock);
 
         /* in native mode send queued data to tty, in
            serial mode nothing needs to be done here */
@@ -1419,7 +1417,7 @@ static void garmin_unthrottle(struct tty_struct *tty)
                 garmin_flush_queue(garmin_data_p);
 
         if (0 != (garmin_data_p->flags & FLAGS_BULK_IN_ACTIVE)) {
-                status = usb_submit_urb(port->read_urb, GFP_ATOMIC);
+                status = usb_submit_urb(port->read_urb, GFP_KERNEL);
                 if (status)
                         dev_err(&port->dev,
                                 "%s - failed resubmitting read urb, error %d\n",