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/symbolserial.c b/drivers/usb/serial/symbolserial.c
index f25e54526843..b282c0f2d8e5 100644
--- a/drivers/usb/serial/symbolserial.c
+++ b/drivers/usb/serial/symbolserial.c
@@ -165,33 +165,31 @@ static void symbol_throttle(struct tty_struct *tty)
 {
         struct usb_serial_port *port = tty->driver_data;
         struct symbol_private *priv = usb_get_serial_data(port->serial);
-        unsigned long flags;
 
         dbg("%s - port %d", __func__, port->number);
-        spin_lock_irqsave(&priv->lock, flags);
+        spin_lock_irq(&priv->lock);
         priv->throttled = true;
-        spin_unlock_irqrestore(&priv->lock, flags);
+        spin_unlock_irq(&priv->lock);
 }
 
 static void symbol_unthrottle(struct tty_struct *tty)
 {
         struct usb_serial_port *port = tty->driver_data;
         struct symbol_private *priv = usb_get_serial_data(port->serial);
-        unsigned long flags;
         int result;
         bool was_throttled;
 
         dbg("%s - port %d", __func__, port->number);
 
-        spin_lock_irqsave(&priv->lock, flags);
+        spin_lock_irq(&priv->lock);
         priv->throttled = false;
         was_throttled = priv->actually_throttled;
         priv->actually_throttled = false;
-        spin_unlock_irqrestore(&priv->lock, flags);
+        spin_unlock_irq(&priv->lock);
 
         priv->int_urb->dev = port->serial->dev;
         if (was_throttled) {
-                result = usb_submit_urb(priv->int_urb, GFP_ATOMIC);
+                result = usb_submit_urb(priv->int_urb, GFP_KERNEL);
                 if (result)
                         dev_err(&port->dev,
                                 "%s - failed submitting read urb, error %d\n",