Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 955 insertions, 0 deletions

diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c
new file mode 100644
index 000000000..dc2b39810
--- /dev/null
+++ b/drivers/usb/serial/quatech2.c
@@ -0,0 +1,955 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * usb-serial driver for Quatech USB 2 devices
+ *
+ * Copyright (C) 2012 Bill Pemberton (wfp5p@virginia.edu)
+ *
+ *  These devices all have only 1 bulk in and 1 bulk out that is shared
+ *  for all serial ports.
+ *
+ */
+
+#include <linux/unaligned.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/module.h>
+#include <linux/serial.h>
+#include <linux/usb.h>
+#include <linux/usb/serial.h>
+#include <linux/serial_reg.h>
+
+/* default urb timeout for usb operations */
+#define QT2_USB_TIMEOUT USB_CTRL_SET_TIMEOUT
+
+#define QT_OPEN_CLOSE_CHANNEL       0xca
+#define QT_SET_GET_DEVICE           0xc2
+#define QT_SET_GET_REGISTER         0xc0
+#define QT_GET_SET_PREBUF_TRIG_LVL  0xcc
+#define QT_SET_ATF                  0xcd
+#define QT_TRANSFER_IN              0xc0
+#define QT_HW_FLOW_CONTROL_MASK     0xc5
+#define QT_SW_FLOW_CONTROL_MASK     0xc6
+#define QT2_BREAK_CONTROL	    0xc8
+#define QT2_GET_SET_UART            0xc1
+#define QT2_FLUSH_DEVICE	    0xc4
+#define QT2_GET_SET_QMCR            0xe1
+#define QT2_QMCR_RS232              0x40
+#define QT2_QMCR_RS422              0x10
+
+#define  SERIAL_CRTSCTS ((UART_MCR_RTS << 8) | UART_MSR_CTS)
+
+#define  SERIAL_EVEN_PARITY         (UART_LCR_PARITY | UART_LCR_EPAR)
+
+/* status bytes for the device */
+#define QT2_CONTROL_BYTE    0x1b
+#define QT2_LINE_STATUS     0x00  /* following 1 byte is line status */
+#define QT2_MODEM_STATUS    0x01  /* following 1 byte is modem status */
+#define QT2_XMIT_HOLD       0x02  /* following 2 bytes are ?? */
+#define QT2_CHANGE_PORT     0x03  /* following 1 byte is port to change to */
+#define QT2_REC_FLUSH       0x04  /* no following info */
+#define QT2_XMIT_FLUSH      0x05  /* no following info */
+#define QT2_CONTROL_ESCAPE  0xff  /* pass through previous 2 control bytes */
+
+#define  MAX_BAUD_RATE              921600
+#define  DEFAULT_BAUD_RATE          9600
+
+#define QT2_READ_BUFFER_SIZE    512  /* size of read buffer */
+#define QT2_WRITE_BUFFER_SIZE   512  /* size of write buffer */
+#define QT2_WRITE_CONTROL_SIZE  5    /* control bytes used for a write */
+
+#define DRIVER_DESC "Quatech 2nd gen USB to Serial Driver"
+
+#define	USB_VENDOR_ID_QUATECH	0x061d
+#define QUATECH_SSU2_100	0xC120	/* RS232 single port */
+#define QUATECH_DSU2_100	0xC140	/* RS232 dual port */
+#define QUATECH_DSU2_400	0xC150	/* RS232/422/485 dual port */
+#define QUATECH_QSU2_100	0xC160	/* RS232 four port */
+#define QUATECH_QSU2_400	0xC170	/* RS232/422/485 four port */
+#define QUATECH_ESU2_100	0xC1A0	/* RS232 eight port */
+#define QUATECH_ESU2_400	0xC180	/* RS232/422/485 eight port */
+
+struct qt2_device_detail {
+	int product_id;
+	int num_ports;
+};
+
+#define QT_DETAILS(prod, ports)	\
+	.product_id = (prod),   \
+	.num_ports = (ports)
+
+static const struct qt2_device_detail qt2_device_details[] = {
+	{QT_DETAILS(QUATECH_SSU2_100, 1)},
+	{QT_DETAILS(QUATECH_DSU2_400, 2)},
+	{QT_DETAILS(QUATECH_DSU2_100, 2)},
+	{QT_DETAILS(QUATECH_QSU2_400, 4)},
+	{QT_DETAILS(QUATECH_QSU2_100, 4)},
+	{QT_DETAILS(QUATECH_ESU2_400, 8)},
+	{QT_DETAILS(QUATECH_ESU2_100, 8)},
+	{QT_DETAILS(0, 0)}	/* Terminating entry */
+};
+
+static const struct usb_device_id id_table[] = {
+	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_SSU2_100)},
+	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_DSU2_100)},
+	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_DSU2_400)},
+	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_QSU2_100)},
+	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_QSU2_400)},
+	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_ESU2_100)},
+	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_ESU2_400)},
+	{}			/* Terminating entry */
+};
+MODULE_DEVICE_TABLE(usb, id_table);
+
+struct qt2_serial_private {
+	unsigned char current_port;  /* current port for incoming data */
+
+	struct urb	*read_urb;   /* shared among all ports */
+	char		*read_buffer;
+};
+
+struct qt2_port_private {
+	u8   device_port;
+
+	spinlock_t urb_lock;
+	bool       urb_in_use;
+	struct urb *write_urb;
+	char       *write_buffer;
+
+	spinlock_t  lock;
+	u8          shadowLSR;
+	u8          shadowMSR;
+
+	struct usb_serial_port *port;
+};
+
+static void qt2_update_lsr(struct usb_serial_port *port, unsigned char *ch);
+static void qt2_update_msr(struct usb_serial_port *port, unsigned char *ch);
+static void qt2_write_bulk_callback(struct urb *urb);
+static void qt2_read_bulk_callback(struct urb *urb);
+
+static void qt2_release(struct usb_serial *serial)
+{
+	struct qt2_serial_private *serial_priv;
+
+	serial_priv = usb_get_serial_data(serial);
+
+	usb_kill_urb(serial_priv->read_urb);
+	usb_free_urb(serial_priv->read_urb);
+	kfree(serial_priv->read_buffer);
+	kfree(serial_priv);
+}
+
+static inline int calc_baud_divisor(int baudrate)
+{
+	int divisor, rem;
+
+	divisor = MAX_BAUD_RATE / baudrate;
+	rem = MAX_BAUD_RATE % baudrate;
+	/* Round to nearest divisor */
+	if (((rem * 2) >= baudrate) && (baudrate != 110))
+		divisor++;
+
+	return divisor;
+}
+
+static inline int qt2_set_port_config(struct usb_device *dev,
+				      unsigned char port_number,
+				      u16 baudrate, u16 lcr)
+{
+	int divisor = calc_baud_divisor(baudrate);
+	u16 index = ((u16) (lcr << 8) | (u16) (port_number));
+
+	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+			       QT2_GET_SET_UART, 0x40,
+			       divisor, index, NULL, 0, QT2_USB_TIMEOUT);
+}
+
+static inline int qt2_control_msg(struct usb_device *dev,
+				  u8 request, u16 data, u16 index)
+{
+	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+			       request, 0x40, data, index,
+			       NULL, 0, QT2_USB_TIMEOUT);
+}
+
+static inline int qt2_getregister(struct usb_device *dev,
+				  u8 uart,
+				  u8 reg,
+				  u8 *data)
+{
+	int ret;
+
+	ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
+			      QT_SET_GET_REGISTER, 0xc0, reg,
+			      uart, data, sizeof(*data), QT2_USB_TIMEOUT);
+	if (ret < (int)sizeof(*data)) {
+		if (ret >= 0)
+			ret = -EIO;
+	}
+
+	return ret;
+}
+
+static inline int qt2_setregister(struct usb_device *dev,
+				  u8 uart, u8 reg, u16 data)
+{
+	u16 value = (data << 8) | reg;
+
+	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+			       QT_SET_GET_REGISTER, 0x40, value, uart,
+			       NULL, 0, QT2_USB_TIMEOUT);
+}
+
+static inline int update_mctrl(struct qt2_port_private *port_priv,
+			       unsigned int set, unsigned int clear)
+{
+	struct usb_serial_port *port = port_priv->port;
+	struct usb_device *dev = port->serial->dev;
+	unsigned urb_value;
+	int status;
+
+	if (((set | clear) & (TIOCM_DTR | TIOCM_RTS)) == 0) {
+		dev_dbg(&port->dev,
+			"update_mctrl - DTR|RTS not being set|cleared\n");
+		return 0;	/* no change */
+	}
+
+	clear &= ~set;	/* 'set' takes precedence over 'clear' */
+	urb_value = 0;
+	if (set & TIOCM_DTR)
+		urb_value |= UART_MCR_DTR;
+	if (set & TIOCM_RTS)
+		urb_value |= UART_MCR_RTS;
+
+	status = qt2_setregister(dev, port_priv->device_port, UART_MCR,
+				 urb_value);
+	if (status < 0)
+		dev_err(&port->dev,
+			"update_mctrl - Error from MODEM_CTRL urb: %i\n",
+			status);
+	return status;
+}
+
+static int qt2_calc_num_ports(struct usb_serial *serial,
+					struct usb_serial_endpoints *epds)
+{
+	struct qt2_device_detail d;
+	int i;
+
+	for (i = 0; d = qt2_device_details[i], d.product_id != 0; i++) {
+		if (d.product_id == le16_to_cpu(serial->dev->descriptor.idProduct))
+			return d.num_ports;
+	}
+
+	/* we didn't recognize the device */
+	dev_err(&serial->dev->dev,
+		 "don't know the number of ports, assuming 1\n");
+
+	return 1;
+}
+
+static void qt2_set_termios(struct tty_struct *tty,
+		            struct usb_serial_port *port,
+		            const struct ktermios *old_termios)
+{
+	struct usb_device *dev = port->serial->dev;
+	struct qt2_port_private *port_priv;
+	struct ktermios *termios = &tty->termios;
+	u16 baud;
+	unsigned int cflag = termios->c_cflag;
+	u16 new_lcr = 0;
+	int status;
+
+	port_priv = usb_get_serial_port_data(port);
+
+	if (cflag & PARENB) {
+		if (cflag & PARODD)
+			new_lcr |= UART_LCR_PARITY;
+		else
+			new_lcr |= SERIAL_EVEN_PARITY;
+	}
+
+	new_lcr |= UART_LCR_WLEN(tty_get_char_size(cflag));
+
+	baud = tty_get_baud_rate(tty);
+	if (!baud)
+		baud = 9600;
+
+	status = qt2_set_port_config(dev, port_priv->device_port, baud,
+				     new_lcr);
+	if (status < 0)
+		dev_err(&port->dev, "%s - qt2_set_port_config failed: %i\n",
+			__func__, status);
+
+	if (cflag & CRTSCTS)
+		status = qt2_control_msg(dev, QT_HW_FLOW_CONTROL_MASK,
+					 SERIAL_CRTSCTS,
+					 port_priv->device_port);
+	else
+		status = qt2_control_msg(dev, QT_HW_FLOW_CONTROL_MASK,
+					 0, port_priv->device_port);
+	if (status < 0)
+		dev_err(&port->dev, "%s - set HW flow control failed: %i\n",
+			__func__, status);
+
+	if (I_IXOFF(tty) || I_IXON(tty)) {
+		u16 x = ((u16) (START_CHAR(tty) << 8) | (u16) (STOP_CHAR(tty)));
+
+		status = qt2_control_msg(dev, QT_SW_FLOW_CONTROL_MASK,
+					 x, port_priv->device_port);
+	} else
+		status = qt2_control_msg(dev, QT_SW_FLOW_CONTROL_MASK,
+					 0, port_priv->device_port);
+
+	if (status < 0)
+		dev_err(&port->dev, "%s - set SW flow control failed: %i\n",
+			__func__, status);
+
+}
+
+static int qt2_open(struct tty_struct *tty, struct usb_serial_port *port)
+{
+	struct usb_serial *serial;
+	struct qt2_port_private *port_priv;
+	u8 *data;
+	u16 device_port;
+	int status;
+	unsigned long flags;
+
+	device_port = port->port_number;
+
+	serial = port->serial;
+
+	port_priv = usb_get_serial_port_data(port);
+
+	/* set the port to RS232 mode */
+	status = qt2_control_msg(serial->dev, QT2_GET_SET_QMCR,
+				 QT2_QMCR_RS232, device_port);
+	if (status < 0) {
+		dev_err(&port->dev,
+			"%s failed to set RS232 mode for port %i error %i\n",
+			__func__, device_port, status);
+		return status;
+	}
+
+	data = kzalloc(2, GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	/* open the port */
+	status = usb_control_msg(serial->dev,
+				 usb_rcvctrlpipe(serial->dev, 0),
+				 QT_OPEN_CLOSE_CHANNEL,
+				 0xc0, 0,
+				 device_port, data, 2, QT2_USB_TIMEOUT);
+
+	if (status < 2) {
+		dev_err(&port->dev, "%s - open port failed %i\n", __func__,
+			status);
+		if (status >= 0)
+			status = -EIO;
+		kfree(data);
+		return status;
+	}
+
+	spin_lock_irqsave(&port_priv->lock, flags);
+	port_priv->shadowLSR = data[0];
+	port_priv->shadowMSR = data[1];
+	spin_unlock_irqrestore(&port_priv->lock, flags);
+
+	kfree(data);
+
+	/* set to default speed and 8bit word size */
+	status = qt2_set_port_config(serial->dev, device_port,
+				     DEFAULT_BAUD_RATE, UART_LCR_WLEN8);
+	if (status < 0) {
+		dev_err(&port->dev, "%s - initial setup failed (%i)\n",
+			__func__, device_port);
+		return status;
+	}
+
+	port_priv->device_port = (u8) device_port;
+
+	if (tty)
+		qt2_set_termios(tty, port, &tty->termios);
+
+	return 0;
+
+}
+
+static void qt2_close(struct usb_serial_port *port)
+{
+	struct usb_serial *serial;
+	struct qt2_port_private *port_priv;
+	int i;
+
+	serial = port->serial;
+	port_priv = usb_get_serial_port_data(port);
+
+	usb_kill_urb(port_priv->write_urb);
+
+	/* flush the port transmit buffer */
+	i = usb_control_msg(serial->dev,
+			    usb_sndctrlpipe(serial->dev, 0),
+			    QT2_FLUSH_DEVICE, 0x40, 1,
+			    port_priv->device_port, NULL, 0, QT2_USB_TIMEOUT);
+
+	if (i < 0)
+		dev_err(&port->dev, "%s - transmit buffer flush failed: %i\n",
+			__func__, i);
+
+	/* flush the port receive buffer */
+	i = usb_control_msg(serial->dev,
+			    usb_sndctrlpipe(serial->dev, 0),
+			    QT2_FLUSH_DEVICE, 0x40, 0,
+			    port_priv->device_port, NULL, 0, QT2_USB_TIMEOUT);
+
+	if (i < 0)
+		dev_err(&port->dev, "%s - receive buffer flush failed: %i\n",
+			__func__, i);
+
+	/* close the port */
+	i = usb_control_msg(serial->dev,
+			    usb_sndctrlpipe(serial->dev, 0),
+			    QT_OPEN_CLOSE_CHANNEL,
+			    0x40, 0,
+			    port_priv->device_port, NULL, 0, QT2_USB_TIMEOUT);
+
+	if (i < 0)
+		dev_err(&port->dev, "%s - close port failed %i\n",
+			__func__, i);
+}
+
+static void qt2_disconnect(struct usb_serial *serial)
+{
+	struct qt2_serial_private *serial_priv = usb_get_serial_data(serial);
+
+	usb_kill_urb(serial_priv->read_urb);
+}
+
+static void qt2_process_status(struct usb_serial_port *port, unsigned char *ch)
+{
+	switch (*ch) {
+	case QT2_LINE_STATUS:
+		qt2_update_lsr(port, ch + 1);
+		break;
+	case QT2_MODEM_STATUS:
+		qt2_update_msr(port, ch + 1);
+		break;
+	}
+}
+
+static void qt2_process_read_urb(struct urb *urb)
+{
+	struct usb_serial *serial;
+	struct qt2_serial_private *serial_priv;
+	struct usb_serial_port *port;
+	bool escapeflag;
+	unsigned char *ch;
+	int i;
+	unsigned char newport;
+	int len = urb->actual_length;
+
+	if (!len)
+		return;
+
+	ch = urb->transfer_buffer;
+	serial = urb->context;
+	serial_priv = usb_get_serial_data(serial);
+	port = serial->port[serial_priv->current_port];
+
+	for (i = 0; i < urb->actual_length; i++) {
+		ch = (unsigned char *)urb->transfer_buffer + i;
+		if ((i <= (len - 3)) &&
+		    (*ch == QT2_CONTROL_BYTE) &&
+		    (*(ch + 1) == QT2_CONTROL_BYTE)) {
+			escapeflag = false;
+			switch (*(ch + 2)) {
+			case QT2_LINE_STATUS:
+			case QT2_MODEM_STATUS:
+				if (i > (len - 4)) {
+					dev_warn(&port->dev,
+						 "%s - status message too short\n",
+						__func__);
+					break;
+				}
+				qt2_process_status(port, ch + 2);
+				i += 3;
+				escapeflag = true;
+				break;
+			case QT2_XMIT_HOLD:
+				if (i > (len - 5)) {
+					dev_warn(&port->dev,
+						 "%s - xmit_empty message too short\n",
+						 __func__);
+					break;
+				}
+				/* bytes_written = (ch[1] << 4) + ch[0]; */
+				i += 4;
+				escapeflag = true;
+				break;
+			case QT2_CHANGE_PORT:
+				if (i > (len - 4)) {
+					dev_warn(&port->dev,
+						 "%s - change_port message too short\n",
+						 __func__);
+					break;
+				}
+				tty_flip_buffer_push(&port->port);
+
+				newport = *(ch + 3);
+
+				if (newport >= serial->num_ports) {
+					dev_err(&port->dev,
+						"%s - port change to invalid port: %i\n",
+						__func__, newport);
+					break;
+				}
+
+				serial_priv->current_port = newport;
+				port = serial->port[serial_priv->current_port];
+				i += 3;
+				escapeflag = true;
+				break;
+			case QT2_REC_FLUSH:
+			case QT2_XMIT_FLUSH:
+				i += 2;
+				escapeflag = true;
+				break;
+			case QT2_CONTROL_ESCAPE:
+				tty_insert_flip_string(&port->port, ch, 2);
+				i += 2;
+				escapeflag = true;
+				break;
+			default:
+				dev_warn(&port->dev,
+					 "%s - unsupported command %i\n",
+					 __func__, *(ch + 2));
+				break;
+			}
+			if (escapeflag)
+				continue;
+		}
+
+		tty_insert_flip_char(&port->port, *ch, TTY_NORMAL);
+	}
+
+	tty_flip_buffer_push(&port->port);
+}
+
+static void qt2_write_bulk_callback(struct urb *urb)
+{
+	struct usb_serial_port *port;
+	struct qt2_port_private *port_priv;
+	unsigned long flags;
+
+	port = urb->context;
+	port_priv = usb_get_serial_port_data(port);
+
+	spin_lock_irqsave(&port_priv->urb_lock, flags);
+
+	port_priv->urb_in_use = false;
+	usb_serial_port_softint(port);
+
+	spin_unlock_irqrestore(&port_priv->urb_lock, flags);
+
+}
+
+static void qt2_read_bulk_callback(struct urb *urb)
+{
+	struct usb_serial *serial = urb->context;
+	int status;
+
+	if (urb->status) {
+		dev_warn(&serial->dev->dev,
+			 "%s - non-zero urb status: %i\n", __func__,
+			 urb->status);
+		return;
+	}
+
+	qt2_process_read_urb(urb);
+
+	status = usb_submit_urb(urb, GFP_ATOMIC);
+	if (status != 0)
+		dev_err(&serial->dev->dev,
+			"%s - resubmit read urb failed: %i\n",
+			__func__, status);
+}
+
+static int qt2_setup_urbs(struct usb_serial *serial)
+{
+	struct usb_serial_port *port0;
+	struct qt2_serial_private *serial_priv;
+	int status;
+
+	port0 = serial->port[0];
+
+	serial_priv = usb_get_serial_data(serial);
+	serial_priv->read_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!serial_priv->read_urb)
+		return -ENOMEM;
+
+	usb_fill_bulk_urb(serial_priv->read_urb, serial->dev,
+			  usb_rcvbulkpipe(serial->dev,
+					  port0->bulk_in_endpointAddress),
+			  serial_priv->read_buffer,
+			  QT2_READ_BUFFER_SIZE,
+			  qt2_read_bulk_callback, serial);
+
+	status = usb_submit_urb(serial_priv->read_urb, GFP_KERNEL);
+	if (status != 0) {
+		dev_err(&serial->dev->dev,
+			"%s - submit read urb failed %i\n", __func__, status);
+		usb_free_urb(serial_priv->read_urb);
+		return status;
+	}
+
+	return 0;
+}
+
+static int qt2_attach(struct usb_serial *serial)
+{
+	struct qt2_serial_private *serial_priv;
+	int status;
+
+	/* power on unit */
+	status = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
+				 0xc2, 0x40, 0x8000, 0, NULL, 0,
+				 QT2_USB_TIMEOUT);
+	if (status < 0) {
+		dev_err(&serial->dev->dev,
+			"%s - failed to power on unit: %i\n", __func__, status);
+		return status;
+	}
+
+	serial_priv = kzalloc_obj(*serial_priv);
+	if (!serial_priv)
+		return -ENOMEM;
+
+	serial_priv->read_buffer = kmalloc(QT2_READ_BUFFER_SIZE, GFP_KERNEL);
+	if (!serial_priv->read_buffer) {
+		status = -ENOMEM;
+		goto err_buf;
+	}
+
+	usb_set_serial_data(serial, serial_priv);
+
+	status = qt2_setup_urbs(serial);
+	if (status != 0)
+		goto attach_failed;
+
+	return 0;
+
+attach_failed:
+	kfree(serial_priv->read_buffer);
+err_buf:
+	kfree(serial_priv);
+	return status;
+}
+
+static int qt2_port_probe(struct usb_serial_port *port)
+{
+	struct usb_serial *serial = port->serial;
+	struct qt2_port_private *port_priv;
+	u8 bEndpointAddress;
+
+	port_priv = kzalloc_obj(*port_priv);
+	if (!port_priv)
+		return -ENOMEM;
+
+	spin_lock_init(&port_priv->lock);
+	spin_lock_init(&port_priv->urb_lock);
+	port_priv->port = port;
+
+	port_priv->write_buffer = kmalloc(QT2_WRITE_BUFFER_SIZE, GFP_KERNEL);
+	if (!port_priv->write_buffer)
+		goto err_buf;
+
+	port_priv->write_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!port_priv->write_urb)
+		goto err_urb;
+
+	bEndpointAddress = serial->port[0]->bulk_out_endpointAddress;
+	usb_fill_bulk_urb(port_priv->write_urb, serial->dev,
+				usb_sndbulkpipe(serial->dev, bEndpointAddress),
+				port_priv->write_buffer,
+				QT2_WRITE_BUFFER_SIZE,
+				qt2_write_bulk_callback, port);
+
+	usb_set_serial_port_data(port, port_priv);
+
+	return 0;
+err_urb:
+	kfree(port_priv->write_buffer);
+err_buf:
+	kfree(port_priv);
+	return -ENOMEM;
+}
+
+static void qt2_port_remove(struct usb_serial_port *port)
+{
+	struct qt2_port_private *port_priv;
+
+	port_priv = usb_get_serial_port_data(port);
+	usb_free_urb(port_priv->write_urb);
+	kfree(port_priv->write_buffer);
+	kfree(port_priv);
+}
+
+static int qt2_tiocmget(struct tty_struct *tty)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	struct usb_device *dev = port->serial->dev;
+	struct qt2_port_private *port_priv = usb_get_serial_port_data(port);
+	u8 *d;
+	int r;
+
+	d = kzalloc(2, GFP_KERNEL);
+	if (!d)
+		return -ENOMEM;
+
+	r = qt2_getregister(dev, port_priv->device_port, UART_MCR, d);
+	if (r < 0)
+		goto mget_out;
+
+	r = qt2_getregister(dev, port_priv->device_port, UART_MSR, d + 1);
+	if (r < 0)
+		goto mget_out;
+
+	r = (d[0] & UART_MCR_DTR ? TIOCM_DTR : 0) |
+	    (d[0] & UART_MCR_RTS ? TIOCM_RTS : 0) |
+	    (d[1] & UART_MSR_CTS ? TIOCM_CTS : 0) |
+	    (d[1] & UART_MSR_DCD ? TIOCM_CAR : 0) |
+	    (d[1] & UART_MSR_RI ? TIOCM_RI : 0) |
+	    (d[1] & UART_MSR_DSR ? TIOCM_DSR : 0);
+
+mget_out:
+	kfree(d);
+	return r;
+}
+
+static int qt2_tiocmset(struct tty_struct *tty,
+			unsigned int set, unsigned int clear)
+{
+	struct qt2_port_private *port_priv;
+
+	port_priv = usb_get_serial_port_data(tty->driver_data);
+	return update_mctrl(port_priv, set, clear);
+}
+
+static int qt2_break_ctl(struct tty_struct *tty, int break_state)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	struct qt2_port_private *port_priv;
+	int status;
+	u16 val;
+
+	port_priv = usb_get_serial_port_data(port);
+
+	val = (break_state == -1) ? 1 : 0;
+
+	status = qt2_control_msg(port->serial->dev, QT2_BREAK_CONTROL,
+				 val, port_priv->device_port);
+	if (status < 0) {
+		dev_warn(&port->dev,
+			 "%s - failed to send control message: %i\n", __func__,
+			 status);
+		return status;
+	}
+
+	return 0;
+}
+
+
+
+static void qt2_dtr_rts(struct usb_serial_port *port, int on)
+{
+	struct usb_device *dev = port->serial->dev;
+	struct qt2_port_private *port_priv = usb_get_serial_port_data(port);
+
+	/* Disable flow control */
+	if (!on) {
+		if (qt2_setregister(dev, port_priv->device_port,
+					   UART_MCR, 0) < 0)
+			dev_warn(&port->dev, "error from flowcontrol urb\n");
+	}
+	/* drop RTS and DTR */
+	if (on)
+		update_mctrl(port_priv, TIOCM_DTR | TIOCM_RTS, 0);
+	else
+		update_mctrl(port_priv, 0, TIOCM_DTR | TIOCM_RTS);
+}
+
+static void qt2_update_msr(struct usb_serial_port *port, unsigned char *ch)
+{
+	struct qt2_port_private *port_priv;
+	u8 newMSR = (u8) *ch;
+	unsigned long flags;
+
+	/* May be called from qt2_process_read_urb() for an unbound port. */
+	port_priv = usb_get_serial_port_data(port);
+	if (!port_priv)
+		return;
+
+	spin_lock_irqsave(&port_priv->lock, flags);
+	port_priv->shadowMSR = newMSR;
+	spin_unlock_irqrestore(&port_priv->lock, flags);
+
+	if (newMSR & UART_MSR_ANY_DELTA) {
+		/* update input line counters */
+		if (newMSR & UART_MSR_DCTS)
+			port->icount.cts++;
+		if (newMSR & UART_MSR_DDSR)
+			port->icount.dsr++;
+		if (newMSR & UART_MSR_DDCD)
+			port->icount.dcd++;
+		if (newMSR & UART_MSR_TERI)
+			port->icount.rng++;
+
+		wake_up_interruptible(&port->port.delta_msr_wait);
+	}
+}
+
+static void qt2_update_lsr(struct usb_serial_port *port, unsigned char *ch)
+{
+	struct qt2_port_private *port_priv;
+	struct async_icount *icount;
+	unsigned long flags;
+	u8 newLSR = (u8) *ch;
+
+	/* May be called from qt2_process_read_urb() for an unbound port. */
+	port_priv = usb_get_serial_port_data(port);
+	if (!port_priv)
+		return;
+
+	if (newLSR & UART_LSR_BI)
+		newLSR &= (u8) (UART_LSR_OE | UART_LSR_BI);
+
+	spin_lock_irqsave(&port_priv->lock, flags);
+	port_priv->shadowLSR = newLSR;
+	spin_unlock_irqrestore(&port_priv->lock, flags);
+
+	icount = &port->icount;
+
+	if (newLSR & UART_LSR_BRK_ERROR_BITS) {
+
+		if (newLSR & UART_LSR_BI)
+			icount->brk++;
+
+		if (newLSR & UART_LSR_OE)
+			icount->overrun++;
+
+		if (newLSR & UART_LSR_PE)
+			icount->parity++;
+
+		if (newLSR & UART_LSR_FE)
+			icount->frame++;
+	}
+
+}
+
+static unsigned int qt2_write_room(struct tty_struct *tty)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	struct qt2_port_private *port_priv;
+	unsigned long flags;
+	unsigned int r;
+
+	port_priv = usb_get_serial_port_data(port);
+
+	spin_lock_irqsave(&port_priv->urb_lock, flags);
+
+	if (port_priv->urb_in_use)
+		r = 0;
+	else
+		r = QT2_WRITE_BUFFER_SIZE - QT2_WRITE_CONTROL_SIZE;
+
+	spin_unlock_irqrestore(&port_priv->urb_lock, flags);
+
+	return r;
+}
+
+static int qt2_write(struct tty_struct *tty,
+		     struct usb_serial_port *port,
+		     const unsigned char *buf, int count)
+{
+	struct qt2_port_private *port_priv;
+	struct urb *write_urb;
+	unsigned char *data;
+	unsigned long flags;
+	int status;
+	int bytes_out = 0;
+
+	port_priv = usb_get_serial_port_data(port);
+
+	if (port_priv->write_urb == NULL) {
+		dev_err(&port->dev, "%s - no output urb\n", __func__);
+		return 0;
+	}
+	write_urb = port_priv->write_urb;
+
+	count = min(count, QT2_WRITE_BUFFER_SIZE - QT2_WRITE_CONTROL_SIZE);
+
+	data = write_urb->transfer_buffer;
+	spin_lock_irqsave(&port_priv->urb_lock, flags);
+	if (port_priv->urb_in_use) {
+		dev_err(&port->dev, "qt2_write - urb is in use\n");
+		goto write_out;
+	}
+
+	*data++ = QT2_CONTROL_BYTE;
+	*data++ = QT2_CONTROL_BYTE;
+	*data++ = port_priv->device_port;
+	put_unaligned_le16(count, data);
+	data += 2;
+	memcpy(data, buf, count);
+
+	write_urb->transfer_buffer_length = count + QT2_WRITE_CONTROL_SIZE;
+
+	status = usb_submit_urb(write_urb, GFP_ATOMIC);
+	if (status == 0) {
+		port_priv->urb_in_use = true;
+		bytes_out += count;
+	}
+
+write_out:
+	spin_unlock_irqrestore(&port_priv->urb_lock, flags);
+	return bytes_out;
+}
+
+
+static struct usb_serial_driver qt2_device = {
+	.driver = {
+		.name = "quatech-serial",
+	},
+	.description	     = DRIVER_DESC,
+	.id_table	     = id_table,
+	.open		     = qt2_open,
+	.close		     = qt2_close,
+	.write               = qt2_write,
+	.write_room          = qt2_write_room,
+	.calc_num_ports      = qt2_calc_num_ports,
+	.attach              = qt2_attach,
+	.release             = qt2_release,
+	.disconnect          = qt2_disconnect,
+	.port_probe          = qt2_port_probe,
+	.port_remove         = qt2_port_remove,
+	.dtr_rts             = qt2_dtr_rts,
+	.break_ctl           = qt2_break_ctl,
+	.tiocmget            = qt2_tiocmget,
+	.tiocmset            = qt2_tiocmset,
+	.tiocmiwait          = usb_serial_generic_tiocmiwait,
+	.get_icount	     = usb_serial_generic_get_icount,
+	.set_termios         = qt2_set_termios,
+};
+
+static struct usb_serial_driver *const serial_drivers[] = {
+	&qt2_device, NULL
+};
+
+module_usb_serial_driver(serial_drivers, id_table);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL v2");