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https://github.com/Fishwaldo/Star64_linux.git
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USB: serial: remove multi-urb write from generic driver
Remove multi-urb write from the generic driver and simplify the prepare_write_buffer prototype: int (*prepare_write_buffer)(struct usb_serial_port *port, void *dest, size_t size); The default implementation simply fills dest with data from port write fifo but drivers can override it if they need to process the outgoing data (e.g. add headers). Turn ftdi_sio into a generic fifo-based driver, which lowers CPU usage significantly for small writes while retaining maximum throughput. Signed-off-by: Johan Hovold <jhovold@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Johan Hovold
Greg Kroah-Hartman
parent
27c7acf220
commit
c23e5fc1f7
4 changed files with 47 additions and 175 deletions
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@ -26,8 +26,6 @@
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static int debug;
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#define MAX_TX_URBS 40
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#ifdef CONFIG_USB_SERIAL_GENERIC
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static int generic_probe(struct usb_interface *interface,
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@ -172,90 +170,9 @@ void usb_serial_generic_close(struct usb_serial_port *port)
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EXPORT_SYMBOL_GPL(usb_serial_generic_close);
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int usb_serial_generic_prepare_write_buffer(struct usb_serial_port *port,
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void **dest, size_t size, const void *src, size_t count)
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void *dest, size_t size)
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{
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if (!*dest) {
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size = count;
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*dest = kmalloc(count, GFP_ATOMIC);
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if (!*dest) {
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dev_err(&port->dev, "%s - could not allocate buffer\n",
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__func__);
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return -ENOMEM;
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}
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}
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if (src) {
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count = size;
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memcpy(*dest, src, size);
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} else {
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count = kfifo_out_locked(&port->write_fifo, *dest, size,
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&port->lock);
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}
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return count;
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}
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EXPORT_SYMBOL_GPL(usb_serial_generic_prepare_write_buffer);
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static int usb_serial_multi_urb_write(struct tty_struct *tty,
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struct usb_serial_port *port, const unsigned char *buf, int count)
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{
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unsigned long flags;
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struct urb *urb;
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void *buffer;
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int status;
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spin_lock_irqsave(&port->lock, flags);
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if (port->tx_urbs == MAX_TX_URBS) {
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spin_unlock_irqrestore(&port->lock, flags);
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dbg("%s - write limit hit", __func__);
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return 0;
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}
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port->tx_urbs++;
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spin_unlock_irqrestore(&port->lock, flags);
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urb = usb_alloc_urb(0, GFP_ATOMIC);
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if (!urb) {
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dev_err(&port->dev, "%s - no free urbs available\n", __func__);
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status = -ENOMEM;
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goto err_urb;
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}
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buffer = NULL;
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count = min_t(int, count, PAGE_SIZE);
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count = port->serial->type->prepare_write_buffer(port, &buffer, 0,
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buf, count);
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if (count < 0) {
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status = count;
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goto err_buf;
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}
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usb_serial_debug_data(debug, &port->dev, __func__, count, buffer);
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usb_fill_bulk_urb(urb, port->serial->dev,
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usb_sndbulkpipe(port->serial->dev,
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port->bulk_out_endpointAddress),
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buffer, count,
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port->serial->type->write_bulk_callback, port);
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status = usb_submit_urb(urb, GFP_ATOMIC);
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if (status) {
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dev_err(&port->dev, "%s - error submitting urb: %d\n",
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__func__, status);
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goto err;
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}
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spin_lock_irqsave(&port->lock, flags);
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port->tx_bytes += urb->transfer_buffer_length;
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spin_unlock_irqrestore(&port->lock, flags);
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usb_free_urb(urb);
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return count;
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err:
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kfree(buffer);
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err_buf:
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usb_free_urb(urb);
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err_urb:
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spin_lock_irqsave(&port->lock, flags);
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port->tx_urbs--;
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spin_unlock_irqrestore(&port->lock, flags);
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return status;
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return kfifo_out_locked(&port->write_fifo, dest, size, &port->lock);
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}
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/**
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@ -286,8 +203,8 @@ retry:
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urb = port->write_urbs[i];
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count = port->serial->type->prepare_write_buffer(port,
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&urb->transfer_buffer,
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port->bulk_out_size, NULL, 0);
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urb->transfer_buffer,
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port->bulk_out_size);
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urb->transfer_buffer_length = count;
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usb_serial_debug_data(debug, &port->dev, __func__, count,
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urb->transfer_buffer);
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@ -328,7 +245,6 @@ retry:
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int usb_serial_generic_write(struct tty_struct *tty,
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struct usb_serial_port *port, const unsigned char *buf, int count)
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{
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struct usb_serial *serial = port->serial;
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int result;
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dbg("%s - port %d", __func__, port->number);
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@ -340,23 +256,18 @@ int usb_serial_generic_write(struct tty_struct *tty,
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if (!count)
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return 0;
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if (serial->type->multi_urb_write)
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return usb_serial_multi_urb_write(tty, port, buf, count);
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count = kfifo_in_locked(&port->write_fifo, buf, count, &port->lock);
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result = usb_serial_generic_write_start(port);
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if (result)
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return result;
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if (result >= 0)
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result = count;
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return result;
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return count;
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}
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EXPORT_SYMBOL_GPL(usb_serial_generic_write);
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int usb_serial_generic_write_room(struct tty_struct *tty)
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{
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struct usb_serial_port *port = tty->driver_data;
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struct usb_serial *serial = port->serial;
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unsigned long flags;
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int room;
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@ -366,10 +277,7 @@ int usb_serial_generic_write_room(struct tty_struct *tty)
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return 0;
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spin_lock_irqsave(&port->lock, flags);
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if (serial->type->multi_urb_write)
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room = (MAX_TX_URBS - port->tx_urbs) * PAGE_SIZE;
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else
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room = kfifo_avail(&port->write_fifo);
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room = kfifo_avail(&port->write_fifo);
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spin_unlock_irqrestore(&port->lock, flags);
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dbg("%s - returns %d", __func__, room);
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@ -379,7 +287,6 @@ int usb_serial_generic_write_room(struct tty_struct *tty)
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int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
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{
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struct usb_serial_port *port = tty->driver_data;
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struct usb_serial *serial = port->serial;
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unsigned long flags;
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int chars;
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@ -389,10 +296,7 @@ int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
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return 0;
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spin_lock_irqsave(&port->lock, flags);
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if (serial->type->multi_urb_write)
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chars = port->tx_bytes;
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else
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chars = kfifo_len(&port->write_fifo) + port->tx_bytes;
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chars = kfifo_len(&port->write_fifo) + port->tx_bytes;
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spin_unlock_irqrestore(&port->lock, flags);
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dbg("%s - returns %d", __func__, chars);
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@ -479,35 +383,25 @@ void usb_serial_generic_write_bulk_callback(struct urb *urb)
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dbg("%s - port %d", __func__, port->number);
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if (port->serial->type->multi_urb_write) {
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kfree(urb->transfer_buffer);
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for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
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if (port->write_urbs[i] == urb)
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break;
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spin_lock_irqsave(&port->lock, flags);
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port->tx_bytes -= urb->transfer_buffer_length;
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set_bit(i, &port->write_urbs_free);
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spin_unlock_irqrestore(&port->lock, flags);
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if (status) {
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dbg("%s - non-zero urb status: %d", __func__, status);
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spin_lock_irqsave(&port->lock, flags);
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port->tx_bytes -= urb->transfer_buffer_length;
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port->tx_urbs--;
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kfifo_reset_out(&port->write_fifo);
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spin_unlock_irqrestore(&port->lock, flags);
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} else {
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for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
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if (port->write_urbs[i] == urb)
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break;
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spin_lock_irqsave(&port->lock, flags);
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port->tx_bytes -= urb->transfer_buffer_length;
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set_bit(i, &port->write_urbs_free);
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spin_unlock_irqrestore(&port->lock, flags);
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if (status) {
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spin_lock_irqsave(&port->lock, flags);
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kfifo_reset_out(&port->write_fifo);
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spin_unlock_irqrestore(&port->lock, flags);
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} else {
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usb_serial_generic_write_start(port);
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}
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usb_serial_generic_write_start(port);
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}
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if (status)
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dbg("%s - non-zero urb status: %d", __func__, status);
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usb_serial_port_softint(port);
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}
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EXPORT_SYMBOL_GPL(usb_serial_generic_write_bulk_callback);
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