+static int usb_serial_multi_urb_write(struct tty_struct *tty,
+ struct usb_serial_port *port, const unsigned char *buf, int count)
+{
+ unsigned long flags;
+ struct urb *urb;
+ unsigned char *buffer;
+ int status;
+ int towrite;
+ int bwrite = 0;
+
+ dbg("%s - port %d", __func__, port->number);
+
+ if (count == 0)
+ dbg("%s - write request of 0 bytes", __func__);
+
+ while (count > 0) {
+ towrite = (count > port->bulk_out_size) ?
+ port->bulk_out_size : count;
+ spin_lock_irqsave(&port->lock, flags);
+ if (port->urbs_in_flight >
+ port->serial->type->max_in_flight_urbs) {
+ spin_unlock_irqrestore(&port->lock, flags);
+ dbg("%s - write limit hit\n", __func__);
+ return bwrite;
+ }
+ port->tx_bytes_flight += towrite;
+ port->urbs_in_flight++;
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ buffer = kmalloc(towrite, GFP_ATOMIC);
+ if (!buffer) {
+ dev_err(&port->dev,
+ "%s ran out of kernel memory for urb ...\n", __func__);
+ goto error_no_buffer;
+ }
+
+ urb = usb_alloc_urb(0, GFP_ATOMIC);
+ if (!urb) {
+ dev_err(&port->dev, "%s - no more free urbs\n",
+ __func__);
+ goto error_no_urb;
+ }
+
+ /* Copy data */
+ memcpy(buffer, buf + bwrite, towrite);
+ usb_serial_debug_data(debug, &port->dev, __func__,
+ towrite, buffer);
+ /* fill the buffer and send it */
+ usb_fill_bulk_urb(urb, port->serial->dev,
+ usb_sndbulkpipe(port->serial->dev,
+ port->bulk_out_endpointAddress),
+ buffer, towrite,
+ usb_serial_generic_write_bulk_callback, port);
+
+ status = usb_submit_urb(urb, GFP_ATOMIC);
+ if (status) {
+ dev_err(&port->dev,
+ "%s - failed submitting write urb, error %d\n",
+ __func__, status);
+ goto error;
+ }
+
+ /* This urb is the responsibility of the host driver now */
+ usb_free_urb(urb);
+ dbg("%s write: %d", __func__, towrite);
+ count -= towrite;
+ bwrite += towrite;
+ }
+ return bwrite;
+
+error:
+ usb_free_urb(urb);
+error_no_urb:
+ kfree(buffer);
+error_no_buffer:
+ spin_lock_irqsave(&port->lock, flags);
+ port->urbs_in_flight--;
+ port->tx_bytes_flight -= towrite;
+ spin_unlock_irqrestore(&port->lock, flags);
+ return bwrite;
+}
+