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USB: serial: clean up read processing in generic driver

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Always process and flush read urb, but only resubmit when not throttled.
The new tty-layer supply plenty of slack so there is really no need to
cache and delay processing of a single urb while throttled.

Note that unthrottle now submits using GFP_KERNEL as we are not in
atomic context (so there is no need to save irq state either).

Note also that the process_read_urb function could be added to
usb_serial_driver should any driver need to do any device specific
processing.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Johan Hovold 2010-03-17 23:05:56 +01:00 committed by Greg Kroah-Hartman
parent 2db6c7698b
commit 0f3d5bae2b
1 changed files with 11 additions and 16 deletions
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27
drivers/usb/serial/generic.c
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@ -408,16 +408,16 @@ int usb_serial_generic_submit_read_urb(struct usb_serial_port *port,
}
EXPORT_SYMBOL_GPL(usb_serial_generic_submit_read_urb);
/* Push data to tty layer and resubmit the bulk read URB */
static void flush_and_resubmit_read_urb(struct usb_serial_port *port)
static void usb_serial_generic_process_read_urb(struct urb *urb)
{
struct urb *urb = port->read_urb;
struct tty_struct *tty = tty_port_tty_get(&port->port);
struct usb_serial_port *port = urb->context;
struct tty_struct *tty;
char *ch = (char *)urb->transfer_buffer;
int i;
tty = tty_port_tty_get(&port->port);
if (!tty)
goto done;
return;
/* The per character mucking around with sysrq path it too slow for
stuff like 3G modems, so shortcircuit it in the 99.9999999% of cases
@ -425,7 +425,6 @@ static void flush_and_resubmit_read_urb(struct usb_serial_port *port)
if (!port->port.console || !port->sysrq)
tty_insert_flip_string(tty, ch, urb->actual_length);
else {
/* Push data to tty */
for (i = 0; i < urb->actual_length; i++, ch++) {
if (!usb_serial_handle_sysrq_char(tty, port, *ch))
tty_insert_flip_char(tty, *ch, TTY_NORMAL);
@ -433,8 +432,6 @@ static void flush_and_resubmit_read_urb(struct usb_serial_port *port)
}
tty_flip_buffer_push(tty);
tty_kref_put(tty);
done:
usb_serial_generic_submit_read_urb(port, GFP_ATOMIC);
}
void usb_serial_generic_read_bulk_callback(struct urb *urb)
@ -454,13 +451,14 @@ void usb_serial_generic_read_bulk_callback(struct urb *urb)
usb_serial_debug_data(debug, &port->dev, __func__,
urb->actual_length, data);
usb_serial_generic_process_read_urb(urb);
/* Throttle the device if requested by tty */
spin_lock_irqsave(&port->lock, flags);
port->throttled = port->throttle_req;
if (!port->throttled) {
spin_unlock_irqrestore(&port->lock, flags);
flush_and_resubmit_read_urb(port);
usb_serial_generic_submit_read_urb(port, GFP_ATOMIC);
} else
spin_unlock_irqrestore(&port->lock, flags);
}
@ -523,20 +521,17 @@ void usb_serial_generic_unthrottle(struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
int was_throttled;
unsigned long flags;
dbg("%s - port %d", __func__, port->number);
/* Clear the throttle flags */
spin_lock_irqsave(&port->lock, flags);
spin_lock_irq(&port->lock);
was_throttled = port->throttled;
port->throttled = port->throttle_req = 0;
spin_unlock_irqrestore(&port->lock, flags);
spin_unlock_irq(&port->lock);
if (was_throttled) {
/* Resume reading from device */
flush_and_resubmit_read_urb(port);
}
if (was_throttled)
usb_serial_generic_submit_read_urb(port, GFP_KERNEL);
}
#ifdef CONFIG_MAGIC_SYSRQ