usb serial: more fixes and groundwork for tty changes

 - If a termios change fails due to lack of memory we should copy the
   old settings back over as the device has not changed
 - Note various locking problems
 - kl5kusb105 had various remaining tty flag handling problems
 - Make safe_serial use tty_insert_flip_string not open coded loops
 - set termios speed properly in usb_serial

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

16 files changed, 93 insertions, 67 deletions

diff --git a/drivers/usb/serial/ark3116.c b/drivers/usb/serial/ark3116.c
index 9d708b22e955..599ab2e548a7 100644
--- a/drivers/usb/serial/ark3116.c
+++ b/drivers/usb/serial/ark3116.c
@@ -192,6 +192,7 @@ static void ark3116_set_termios(struct usb_serial_port *port,
         buf = kmalloc(1, GFP_KERNEL);
         if (!buf) {
                 dbg("error kmalloc");
+                *port->tty->termios = *old_termios;
                 return;
         }
 
diff --git a/drivers/usb/serial/cyberjack.c b/drivers/usb/serial/cyberjack.c
index 5348e97b52b5..d077534ceaeb 100644
--- a/drivers/usb/serial/cyberjack.c
+++ b/drivers/usb/serial/cyberjack.c
@@ -151,7 +151,7 @@ static void cyberjack_shutdown (struct usb_serial *serial)
         
         dbg("%s", __func__);
 
-        for (i=0; i < serial->num_ports; ++i) {
+        for (i = 0; i < serial->num_ports; ++i) {
                 usb_kill_urb(serial->port[i]->interrupt_in_urb);
                 /* My special items, the standard routines free my urbs */
                 kfree(usb_get_serial_port_data(serial->port[i]));
@@ -209,7 +209,7 @@ static int cyberjack_write (struct usb_serial_port *port, const unsigned char *b
 
         if (count == 0) {
                 dbg("%s - write request of 0 bytes", __func__);
-                return (0);
+                return 0;
         }
 
         spin_lock_bh(&port->lock);
@@ -223,12 +223,12 @@ static int cyberjack_write (struct usb_serial_port *port, const unsigned char *b
 
         spin_lock_irqsave(&priv->lock, flags);
 
-        if( (count+priv->wrfilled)>sizeof(priv->wrbuf) ) {
+        if( (count+priv->wrfilled) > sizeof(priv->wrbuf) ) {
                 /* To much data for buffer. Reset buffer. */
-                priv->wrfilled=0;
-                spin_unlock_irqrestore(&priv->lock, flags);
+                priv->wrfilled = 0;
                 port->write_urb_busy = 0;
-                return (0);
+                spin_unlock_irqrestore(&priv->lock, flags);
+                return 0;
         }
 
         /* Copy data */
@@ -269,8 +269,8 @@ static int cyberjack_write (struct usb_serial_port *port, const unsigned char *b
                 if (result) {
                         err("%s - failed submitting write urb, error %d", __func__, result);
                         /* Throw away data. No better idea what to do with it. */
-                        priv->wrfilled=0;
-                        priv->wrsent=0;
+                        priv->wrfilled = 0;
+                        priv->wrsent = 0;
                         spin_unlock_irqrestore(&priv->lock, flags);
                         port->write_urb_busy = 0;
                         return 0;
@@ -282,8 +282,8 @@ static int cyberjack_write (struct usb_serial_port *port, const unsigned char *b
                 if( priv->wrsent>=priv->wrfilled ) {
                         dbg("%s - buffer cleaned", __func__);
                         memset( priv->wrbuf, 0, sizeof(priv->wrbuf) );
-                        priv->wrfilled=0;
-                        priv->wrsent=0;
+                        priv->wrfilled = 0;
+                        priv->wrsent = 0;
                 }
         }
 
@@ -294,6 +294,7 @@ static int cyberjack_write (struct usb_serial_port *port, const unsigned char *b
 
 static int cyberjack_write_room( struct usb_serial_port *port )
 {
+        /* FIXME: .... */
         return CYBERJACK_LOCAL_BUF_SIZE;
 }
 
@@ -314,7 +315,7 @@ static void cyberjack_read_int_callback( struct urb *urb )
         usb_serial_debug_data(debug, &port->dev, __func__, urb->actual_length, data);
 
         /* React only to interrupts signaling a bulk_in transfer */
-        if( (urb->actual_length==4) && (data[0]==0x01) ) {
+        if( (urb->actual_length == 4) && (data[0] == 0x01) ) {
                 short old_rdtodo;
 
                 /* This is a announcement of coming bulk_ins. */
@@ -450,8 +451,8 @@ static void cyberjack_write_bulk_callback (struct urb *urb)
                 if (result) {
                         err("%s - failed submitting write urb, error %d", __func__, result);
                         /* Throw away data. No better idea what to do with it. */
-                        priv->wrfilled=0;
-                        priv->wrsent=0;
+                        priv->wrfilled = 0;
+                        priv->wrsent = 0;
                         goto exit;
                 }
 
@@ -463,8 +464,8 @@ static void cyberjack_write_bulk_callback (struct urb *urb)
                 if( (priv->wrsent>=priv->wrfilled) || (priv->wrsent>=blksize) ) {
                         dbg("%s - buffer cleaned", __func__);
                         memset( priv->wrbuf, 0, sizeof(priv->wrbuf) );
-                        priv->wrfilled=0;
-                        priv->wrsent=0;
+                        priv->wrfilled = 0;
+                        priv->wrsent = 0;
                 }
         }
 
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 2078667db4aa..65765ce76251 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -262,13 +262,14 @@ int usb_serial_generic_write_room (struct usb_serial_port *port)
 
         dbg("%s - port %d", __func__, port->number);
 
+        /* FIXME: Locking */
         if (serial->num_bulk_out) {
                 if (!(port->write_urb_busy))
                         room = port->bulk_out_size;
         }
 
         dbg("%s - returns %d", __func__, room);
-        return (room);
+        return room;
 }
 
 int usb_serial_generic_chars_in_buffer (struct usb_serial_port *port)
@@ -278,6 +279,7 @@ int usb_serial_generic_chars_in_buffer (struct usb_serial_port *port)
 
         dbg("%s - port %d", __func__, port->number);
 
+        /* FIXME: Locking */
         if (serial->num_bulk_out) {
                 if (port->write_urb_busy)
                         chars = port->write_urb->transfer_buffer_length;
@@ -368,7 +370,6 @@ void usb_serial_generic_write_bulk_callback (struct urb *urb)
                     __func__, status);
                 return;
         }
-
         usb_serial_port_softint(port);
 }
 EXPORT_SYMBOL_GPL(usb_serial_generic_write_bulk_callback);
diff --git a/drivers/usb/serial/keyspan.c b/drivers/usb/serial/keyspan.c
index 857c5312555a..0d122feb2b22 100644
--- a/drivers/usb/serial/keyspan.c
+++ b/drivers/usb/serial/keyspan.c
@@ -1187,6 +1187,7 @@ static int keyspan_write_room (struct usb_serial_port *port)
         p_priv = usb_get_serial_port_data(port);
         d_details = p_priv->device_details;
 
+        /* FIXME: locking */
         if (d_details->msg_format == msg_usa90)
                 data_len = 64;
         else
@@ -1203,13 +1204,13 @@ static int keyspan_write_room (struct usb_serial_port *port)
                         if (this_urb->status != -EINPROGRESS)
                                 return (data_len);
         }
-        return (0);
+        return 0;
 }
 
 
 static int keyspan_chars_in_buffer (struct usb_serial_port *port)
 {
-        return (0);
+        return 0;
 }
 
 
@@ -1289,7 +1290,7 @@ static int keyspan_open (struct usb_serial_port *port, struct file *filp)
         //mdelay(100);
         //keyspan_set_termios(port, NULL);
 
-        return (0);
+        return 0;
 }
 
 static inline void stop_urb(struct urb *urb)
@@ -2006,7 +2007,7 @@ static int keyspan_usa26_send_setup(struct usb_serial *serial,
         }
 #endif
 
-        return (0);
+        return 0;
 }
 
 static int keyspan_usa28_send_setup(struct usb_serial *serial,
@@ -2131,7 +2132,7 @@ static int keyspan_usa28_send_setup(struct usb_serial *serial,
         }
 #endif
 
-        return (0);
+        return 0;
 }
 
 static int keyspan_usa49_send_setup(struct usb_serial *serial,
@@ -2317,7 +2318,7 @@ static int keyspan_usa49_send_setup(struct usb_serial *serial,
         }
 #endif
 
-        return (0);
+        return 0;
 }
 
 static int keyspan_usa90_send_setup(struct usb_serial *serial,
@@ -2455,7 +2456,7 @@ static int keyspan_usa90_send_setup(struct usb_serial *serial,
         if ((err = usb_submit_urb(this_urb, GFP_ATOMIC)) != 0) {
                 dbg("%s - usb_submit_urb(setup) failed (%d)", __func__, err);
         }
-        return (0);
+        return 0;
 }
 
 static int keyspan_usa67_send_setup(struct usb_serial *serial,
@@ -2603,7 +2604,7 @@ static int keyspan_usa67_send_setup(struct usb_serial *serial,
         if (err != 0)
                 dbg("%s - usb_submit_urb(setup) failed (%d)", __func__,
                                 err);
-        return (0);
+        return 0;
 }
 
 static void keyspan_send_setup(struct usb_serial_port *port, int reset_port)
@@ -2696,7 +2697,7 @@ static int keyspan_startup (struct usb_serial *serial)
                                 err);
         }
                         
-        return (0);
+        return 0;
 }
 
 static void keyspan_shutdown (struct usb_serial *serial)
diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c
index 6ce292ef1c47..b650fb4754b4 100644
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -636,14 +636,19 @@ static int keyspan_pda_write_room (struct usb_serial_port *port)
 static int keyspan_pda_chars_in_buffer (struct usb_serial_port *port)
 {
         struct keyspan_pda_private *priv;
+        unsigned long flags;
+        int ret = 0;
 
         priv = usb_get_serial_port_data(port);
 
         /* when throttled, return at least WAKEUP_CHARS to tell select() (via
            n_tty.c:normal_poll() ) that we're not writeable. */
+
+        spin_lock_irqsave(&port->lock, flags);
         if (port->write_urb_busy || priv->tx_throttled)
-                return 256;
-        return 0;
+                ret = 256;
+        spin_unlock_irqrestore(&port->lock, flags);
+        return ret;
 }
 
 
diff --git a/drivers/usb/serial/kl5kusb105.c b/drivers/usb/serial/kl5kusb105.c
index 160e19263e25..b3ac045ab408 100644
--- a/drivers/usb/serial/kl5kusb105.c
+++ b/drivers/usb/serial/kl5kusb105.c
@@ -702,12 +702,14 @@ static void klsi_105_set_termios (struct usb_serial_port *port,
                                   struct ktermios *old_termios)
 {
         struct klsi_105_private *priv = usb_get_serial_port_data(port);
-        unsigned int iflag = port->tty->termios->c_iflag;
+        struct tty_struct *tty = port->tty;
+        unsigned int iflag = tty->termios->c_iflag;
         unsigned int old_iflag = old_termios->c_iflag;
-        unsigned int cflag = port->tty->termios->c_cflag;
+        unsigned int cflag = tty->termios->c_cflag;
         unsigned int old_cflag = old_termios->c_cflag;
         struct klsi_105_port_settings cfg;
         unsigned long flags;
+        speed_t baud;
         
         /* lock while we are modifying the settings */
         spin_lock_irqsave (&priv->lock, flags);
@@ -715,6 +717,8 @@ static void klsi_105_set_termios (struct usb_serial_port *port,
         /*
          * Update baud rate
          */
+        baud = tty_get_baud_rate(tty);
+
         if( (cflag & CBAUD) != (old_cflag & CBAUD) ) {
                 /* reassert DTR and (maybe) RTS on transition from B0 */
                 if( (old_cflag & CBAUD) == B0 ) {
@@ -728,8 +732,8 @@ static void klsi_105_set_termios (struct usb_serial_port *port,
                         mct_u232_set_modem_ctrl(serial, priv->control_state);
 #endif
                 }
-                
-                switch(tty_get_baud_rate(port->tty)) {
+        }
+        switch(baud) {
                 case 0: /* handled below */
                         break;
                 case 1200:
@@ -757,25 +761,26 @@ static void klsi_105_set_termios (struct usb_serial_port *port,
                         priv->cfg.baudrate = kl5kusb105a_sio_b115200;
                         break;
                 default:
-                        err("KLSI USB->Serial converter:"
+                        dbg("KLSI USB->Serial converter:"
                             " unsupported baudrate request, using default"
                             " of 9600");
                         priv->cfg.baudrate = kl5kusb105a_sio_b9600;
+                        baud = 9600;
                         break;
-                }
-                if ((cflag & CBAUD) == B0 ) {
-                        dbg("%s: baud is B0", __func__);
-                        /* Drop RTS and DTR */
-                        /* maybe this should be simulated by sending read
-                         * disable and read enable messages?
-                         */
-                        ;
+        }
+        if ((cflag & CBAUD) == B0 ) {
+                dbg("%s: baud is B0", __func__);
+                /* Drop RTS and DTR */
+                /* maybe this should be simulated by sending read
+                 * disable and read enable messages?
+                 */
+                ;
 #if 0
-                        priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
-                        mct_u232_set_modem_ctrl(serial, priv->control_state);
+                priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
+                mct_u232_set_modem_ctrl(serial, priv->control_state);
 #endif
-                }
         }
+        tty_encode_baud_rate(tty, baud, baud);
 
         if ((cflag & CSIZE) != (old_cflag & CSIZE)) {
                 /* set the number of data bits */
@@ -807,6 +812,8 @@ static void klsi_105_set_termios (struct usb_serial_port *port,
         if ((cflag & (PARENB|PARODD)) != (old_cflag & (PARENB|PARODD))
             || (cflag & CSTOPB) != (old_cflag & CSTOPB) ) {
                 
+                /* Not currently supported */
+                tty->termios->c_cflag &= ~(PARENB|PARODD|CSTOPB);
 #if 0
                 priv->last_lcr = 0;
 
@@ -834,6 +841,8 @@ static void klsi_105_set_termios (struct usb_serial_port *port,
             || (iflag & IXON) != (old_iflag & IXON)
             ||  (cflag & CRTSCTS) != (old_cflag & CRTSCTS) ) {
                 
+                /* Not currently supported */
+                tty->termios->c_cflag &= ~CRTSCTS;
                 /* Drop DTR/RTS if no flow control otherwise assert */
 #if 0
                 if ((iflag & IXOFF) || (iflag & IXON) || (cflag & CRTSCTS) )
diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index 74b889bf19cf..50f1fe263338 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -635,6 +635,7 @@ static int mos7720_write_room(struct usb_serial_port *port)
                 return -ENODEV;
         }
 
+        /* FIXME: Locking */
         for (i = 0; i < NUM_URBS; ++i) {
                 if (mos7720_port->write_urb_pool[i] && mos7720_port->write_urb_pool[i]->status != -EINPROGRESS)
                         room += URB_TRANSFER_BUFFER_SIZE;
diff --git a/drivers/usb/serial/navman.c b/drivers/usb/serial/navman.c
index 7cea325d577c..43c8894353bf 100644
--- a/drivers/usb/serial/navman.c
+++ b/drivers/usb/serial/navman.c
@@ -6,6 +6,10 @@
  *      This program is free software; you can redistribute it and/or
  *      modify it under the terms of the GNU General Public License
  *      version 2 as published by the Free Software Foundation.
+ *
+ * TODO:
+ *      Add termios method that uses copy_hw but also kills all echo
+ *      flags as the navman is rx only so cannot echo.
  */
 
 #include <linux/kernel.h>
@@ -106,12 +110,8 @@ static int navman_write(struct usb_serial_port *port,
 
         /*
          * This device can't write any data, only read from the device
-         * so we just silently eat all data sent to us and say it was
-         * successfully sent.
-         * Evil, I know, but do you have a better idea?
          */
-
-        return count;
+        return -EOPNOTSUPP;
 }
 
 static struct usb_serial_driver navman_device = {
diff --git a/drivers/usb/serial/omninet.c b/drivers/usb/serial/omninet.c
index 1b041c59aab2..10090cb52d31 100644
--- a/drivers/usb/serial/omninet.c
+++ b/drivers/usb/serial/omninet.c
@@ -295,8 +295,9 @@ static int omninet_write_room (struct usb_serial_port *port)
         struct usb_serial       *serial = port->serial;
         struct usb_serial_port  *wport  = serial->port[1];
 
-        int room = 0; // Default: no room
+        int room = 0; /* Default: no room */
 
+        /* FIXME: no consistent locking for write_urb_busy */
         if (wport->write_urb_busy)
                 room = wport->bulk_out_size - OMNINET_HEADERLEN;
 
diff --git a/drivers/usb/serial/option.c b/drivers/usb/serial/option.c
index 920241897c95..a83892627d66 100644
--- a/drivers/usb/serial/option.c
+++ b/drivers/usb/serial/option.c
@@ -656,6 +656,7 @@ static int option_write_room(struct usb_serial_port *port)
 
         portdata = usb_get_serial_port_data(port);
 
+
         for (i=0; i < N_OUT_URB; i++) {
                 this_urb = portdata->out_urbs[i];
                 if (this_urb && !test_bit(i, &portdata->out_busy))
@@ -677,6 +678,8 @@ static int option_chars_in_buffer(struct usb_serial_port *port)
 
         for (i=0; i < N_OUT_URB; i++) {
                 this_urb = portdata->out_urbs[i];
+                /* FIXME: This locking is insufficient as this_urb may
+                   go unused during the test */
                 if (this_urb && test_bit(i, &portdata->out_busy))
                         data_len += this_urb->transfer_buffer_length;
         }
diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 2b4ab371c762..c60930ec9341 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -546,6 +546,8 @@ static void pl2303_set_termios(struct usb_serial_port *port,
         buf = kzalloc(7, GFP_KERNEL);
         if (!buf) {
                 dev_err(&port->dev, "%s - out of memory.\n", __func__);
+                /* Report back no change occurred */
+                *port->tty->termios = *old_termios;
                 return;
         }
 
diff --git a/drivers/usb/serial/safe_serial.c b/drivers/usb/serial/safe_serial.c
index 3fe98a52b914..e6acac49a9c8 100644
--- a/drivers/usb/serial/safe_serial.c
+++ b/drivers/usb/serial/safe_serial.c
@@ -198,7 +198,6 @@ static void safe_read_bulk_callback (struct urb *urb)
         struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
         unsigned char *data = urb->transfer_buffer;
         unsigned char length = urb->actual_length;
-        int i;
         int result;
         int status = urb->status;
 
@@ -227,16 +226,10 @@ static void safe_read_bulk_callback (struct urb *urb)
         if (safe) {
                 __u16 fcs;
                 if (!(fcs = fcs_compute10 (data, length, CRC10_INITFCS))) {
-
                         int actual_length = data[length - 2] >> 2;
-
                         if (actual_length <= (length - 2)) {
-
                                 info ("%s - actual: %d", __func__, actual_length);
-
-                                for (i = 0; i < actual_length; i++) {
-                                        tty_insert_flip_char (port->tty, data[i], 0);
-                                }
+                                tty_insert_flip_string(port->tty, data, actual_length);
                                 tty_flip_buffer_push (port->tty);
                         } else {
                                 err ("%s - inconsistent lengths %d:%d", __func__,
@@ -246,9 +239,7 @@ static void safe_read_bulk_callback (struct urb *urb)
                         err ("%s - bad CRC %x", __func__, fcs);
                 }
         } else {
-                for (i = 0; i < length; i++) {
-                        tty_insert_flip_char (port->tty, data[i], 0);
-                }
+                tty_insert_flip_string(port->tty, data, length);
                 tty_flip_buffer_push (port->tty);
         }
 
@@ -260,6 +251,7 @@ static void safe_read_bulk_callback (struct urb *urb)
 
         if ((result = usb_submit_urb (urb, GFP_ATOMIC))) {
                 err ("%s - failed resubmitting read urb, error %d", __func__, result);
+                /* FIXME: Need a mechanism to retry later if this happens */
         }
 }
 
@@ -275,7 +267,7 @@ static int safe_write (struct usb_serial_port *port, const unsigned char *buf, i
 
         if (!port->write_urb) {
                 dbg ("%s - write urb NULL", __func__);
-                return (0);
+                return 0;
         }
 
         dbg ("safe_write write_urb: %d transfer_buffer_length",
@@ -283,11 +275,11 @@ static int safe_write (struct usb_serial_port *port, const unsigned char *buf, i
 
         if (!port->write_urb->transfer_buffer_length) {
                 dbg ("%s - write urb transfer_buffer_length zero", __func__);
-                return (0);
+                return 0;
         }
         if (count == 0) {
                 dbg ("%s - write request of 0 bytes", __func__);
-                return (0);
+                return 0;
         }
         spin_lock_bh(&port->lock);
         if (port->write_urb_busy) {
@@ -359,18 +351,21 @@ static int safe_write (struct usb_serial_port *port, const unsigned char *buf, i
 
 static int safe_write_room (struct usb_serial_port *port)
 {
-        int room = 0;           // Default: no room
+        int room = 0;           /* Default: no room */
+        unsigned long flags;
 
         dbg ("%s", __func__);
 
+        spin_lock_irqsave(&port->lock, flags);
         if (port->write_urb_busy)
                 room = port->bulk_out_size - (safe ? 2 : 0);
+        spin_unlock_irqrestore(&port->lock, flags);
 
         if (room) {
                 dbg ("safe_write_room returns %d", room);
         }
 
-        return (room);
+        return room;
 }
 
 static int safe_startup (struct usb_serial *serial)
diff --git a/drivers/usb/serial/sierra.c b/drivers/usb/serial/sierra.c
index ed30adefff85..23188873eb07 100644
--- a/drivers/usb/serial/sierra.c
+++ b/drivers/usb/serial/sierra.c
@@ -566,6 +566,8 @@ static int sierra_chars_in_buffer(struct usb_serial_port *port)
          * have sent out, but hasn't made it through to the
          * device as we can't see the backend here, so just
          * tell the tty layer that everything is flushed.
+         *
+         * FIXME: should walk the outstanding urbs info
          */
         return 0;
 }
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index baf953d14d82..a9934a3f9845 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -1179,6 +1179,8 @@ static int __init usb_serial_init(void)
         usb_serial_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
         usb_serial_tty_driver->init_termios = tty_std_termios;
         usb_serial_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
+        usb_serial_tty_driver->init_termios.c_ispeed = 9600;
+        usb_serial_tty_driver->init_termios.c_ospeed = 9600;
         tty_set_operations(usb_serial_tty_driver, &serial_ops);
         result = tty_register_driver(usb_serial_tty_driver);
         if (result) {
diff --git a/drivers/usb/serial/visor.c b/drivers/usb/serial/visor.c
index 137df445e296..a100a52a376e 100644
--- a/drivers/usb/serial/visor.c
+++ b/drivers/usb/serial/visor.c
@@ -469,6 +469,8 @@ static int visor_chars_in_buffer (struct usb_serial_port *port)
          * have sent out, but hasn't made it through to the
          * device, so just tell the tty layer that everything
          * is flushed.
+         *
+         * FIXME: Should walk outstanding_urbs
          */
         return 0;
 }
diff --git a/drivers/usb/serial/whiteheat.c b/drivers/usb/serial/whiteheat.c
index fb02424de4a0..6926a81a0ccd 100644
--- a/drivers/usb/serial/whiteheat.c
+++ b/drivers/usb/serial/whiteheat.c
@@ -219,7 +219,7 @@ struct whiteheat_urb_wrap {
 struct whiteheat_private {
         spinlock_t              lock;
         __u8                    flags;
-        __u8                    mcr;
+        __u8                    mcr;            /* FIXME: no locking on mcr */
         struct list_head        rx_urbs_free;
         struct list_head        rx_urbs_submitted;
         struct list_head        rx_urb_q;