1 files changed, 13 insertions, 11 deletions

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index ff8605b4b4be..c02e4602d90a 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -75,7 +75,7 @@ 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 */
         char transmit_empty;    /* If transmitter is empty or not */
         struct usb_serial_port *port;
         __u16 interface;        /* FT2232C, FT2232H or FT4232H port interface
@@ -1982,17 +1982,19 @@ 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;
         }