USB: ftdi_sio: fix race condition in TIOCMIWAIT, and abort of TIOCMIWAIT when the...

[linux-flexiantxendom0.git] / drivers / usb / serial / ftdi_sio.c

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index f2c9ef7..c4cf3f3 100644 (file)
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -75,7 +75,8 @@ struct ftdi_private {
        unsigned long last_dtr_rts;     /* saved modem control outputs */
        struct async_icount     icount;
        wait_queue_head_t delta_msr_wait; /* Used for TIOCMIWAIT */
-       char prev_status, diff_status;        /* Used for TIOCMIWAIT */
+       char prev_status;        /* Used for TIOCMIWAIT */
+       bool dev_gone;        /* Used to abort TIOCMIWAIT */
        char transmit_empty;    /* If transmitter is empty or not */
        struct usb_serial_port *port;
        __u16 interface;        /* FT2232C, FT2232H or FT4232H port interface
@@ -1679,6 +1680,7 @@ static int ftdi_sio_port_probe(struct usb_serial_port *port)
        init_waitqueue_head(&priv->delta_msr_wait);
 
        priv->flags = ASYNC_LOW_LATENCY;
+       priv->dev_gone = false;
 
        if (quirk && quirk->port_probe)
                quirk->port_probe(priv);
@@ -1836,6 +1838,9 @@ static int ftdi_sio_port_remove(struct usb_serial_port *port)
 
        dbg("%s", __func__);
 
+       priv->dev_gone = true;
+       wake_up_interruptible_all(&priv->delta_msr_wait);
+
        remove_sysfs_attrs(port);
 
        kref_put(&priv->kref, ftdi_sio_priv_release);
@@ -1979,17 +1984,19 @@ static int ftdi_process_packet(struct tty_struct *tty,
           N.B. packet may be processed more than once, but differences
           are only processed once.  */
        status = packet[0] & FTDI_STATUS_B0_MASK;
-       if (status & FTDI_RS0_CTS)
-               priv->icount.cts++;
-       if (status & FTDI_RS0_DSR)
-               priv->icount.dsr++;
-       if (status & FTDI_RS0_RI)
-               priv->icount.rng++;
-       if (status & FTDI_RS0_RLSD)
-               priv->icount.dcd++;
        if (status != priv->prev_status) {
-               priv->diff_status |= status ^ priv->prev_status;
-               wake_up_interruptible(&priv->delta_msr_wait);
+               char diff_status = status ^ priv->prev_status;
+
+               if (diff_status & FTDI_RS0_CTS)
+                       priv->icount.cts++;
+               if (diff_status & FTDI_RS0_DSR)
+                       priv->icount.dsr++;
+               if (diff_status & FTDI_RS0_RI)
+                       priv->icount.rng++;
+               if (diff_status & FTDI_RS0_RLSD)
+                       priv->icount.dcd++;
+
+               wake_up_interruptible_all(&priv->delta_msr_wait);
                priv->prev_status = status;
        }
 
@@ -2388,15 +2395,12 @@ static int ftdi_ioctl(struct tty_struct *tty,
         */
        case TIOCMIWAIT:
                cprev = priv->icount;
-               while (1) {
+               while (!priv->dev_gone) {
                        interruptible_sleep_on(&priv->delta_msr_wait);
                        /* see if a signal did it */
                        if (signal_pending(current))
                                return -ERESTARTSYS;
                        cnow = priv->icount;
-                       if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
-                           cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
-                               return -EIO; /* no change => error */
                        if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
                            ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
                            ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
@@ -2405,7 +2409,7 @@ static int ftdi_ioctl(struct tty_struct *tty,
                        }
                        cprev = cnow;
                }
-               /* not reached */
+               return -EIO;
                break;
        case TIOCSERGETLSR:
                return get_lsr_info(port, (struct serial_struct __user *)arg);