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Commit 0f3d5bae authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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USB: serial: clean up read processing in generic driver 



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: default avatarJohan Hovold <jhovold@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 2db6c769

drivers/usb/serial/generic.c

+11 −16
Original line number Original line Diff line number Diff line
@@ -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);

EXPORT_SYMBOL_GPL(usb_serial_generic_submit_read_urb);





/* Push data to tty layer and resubmit the bulk read URB */

static void usb_serial_generic_process_read_urb(struct urb *urb)

static void flush_and_resubmit_read_urb(struct usb_serial_port *port)

{

{

	struct urb *urb = port->read_urb;

	struct usb_serial_port *port = urb->context;

	struct tty_struct *tty = tty_port_tty_get(&port->port);

	struct tty_struct *tty;

	char *ch = (char *)urb->transfer_buffer;

	char *ch = (char *)urb->transfer_buffer;

	int i;

	int i;





	tty = tty_port_tty_get(&port->port);

	if (!tty)

	if (!tty)

		goto done;

		return;





	/* The per character mucking around with sysrq path it too slow for

	/* 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

	   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)

	if (!port->port.console || !port->sysrq)

		tty_insert_flip_string(tty, ch, urb->actual_length);

		tty_insert_flip_string(tty, ch, urb->actual_length);

	else {

	else {

		/* Push data to tty */

		for (i = 0; i < urb->actual_length; i++, ch++) {

		for (i = 0; i < urb->actual_length; i++, ch++) {

			if (!usb_serial_handle_sysrq_char(tty, port, *ch))

			if (!usb_serial_handle_sysrq_char(tty, port, *ch))

				tty_insert_flip_char(tty, *ch, TTY_NORMAL);

				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_flip_buffer_push(tty);

	tty_kref_put(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)

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__,

	usb_serial_debug_data(debug, &port->dev, __func__,

						urb->actual_length, data);

						urb->actual_length, data);

	usb_serial_generic_process_read_urb(urb);





	/* Throttle the device if requested by tty */

	/* Throttle the device if requested by tty */

	spin_lock_irqsave(&port->lock, flags);

	spin_lock_irqsave(&port->lock, flags);

	port->throttled = port->throttle_req;

	port->throttled = port->throttle_req;

	if (!port->throttled) {

	if (!port->throttled) {

		spin_unlock_irqrestore(&port->lock, flags);

		spin_unlock_irqrestore(&port->lock, flags);

		flush_and_resubmit_read_urb(port);

		usb_serial_generic_submit_read_urb(port, GFP_ATOMIC);

	} else

	} else

		spin_unlock_irqrestore(&port->lock, flags);

		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;

	struct usb_serial_port *port = tty->driver_data;

	int was_throttled;

	int was_throttled;

	unsigned long flags;





	dbg("%s - port %d", __func__, port->number);

	dbg("%s - port %d", __func__, port->number);





	/* Clear the throttle flags */

	/* Clear the throttle flags */

	spin_lock_irqsave(&port->lock, flags);

	spin_lock_irq(&port->lock);

	was_throttled = port->throttled;

	was_throttled = port->throttled;

	port->throttled = port->throttle_req = 0;

	port->throttled = port->throttle_req = 0;

	spin_unlock_irqrestore(&port->lock, flags);

	spin_unlock_irq(&port->lock);





	if (was_throttled) {

	if (was_throttled)

		/* Resume reading from device */

		usb_serial_generic_submit_read_urb(port, GFP_KERNEL);

		flush_and_resubmit_read_urb(port);

	}

}

}





#ifdef CONFIG_MAGIC_SYSRQ

#ifdef CONFIG_MAGIC_SYSRQ