tty: n_hdlc not atomic use tty->flags.

N_HDLC can spoil tty->flags because use not atomic operations on tty->flags.
I use n_hdlc line discipline and it happens.

Signed-off-by: Ilya Zykov <ilya@ilyx.ru>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/tty/n_hdlc.c b/drivers/tty/n_hdlc.c
index cea56033b34c2b490e796ae75df0fbea4e550a3f..a09ce3ef5d748f9455ebba56b38aa97f097e8187 100644 (file)
--- a/drivers/tty/n_hdlc.c
+++ b/drivers/tty/n_hdlc.c
@@ -417,7 +417,7 @@ static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)
                                __FILE__,__LINE__,tbuf,tbuf->count);
                        
                /* Send the next block of data to device */
-               tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
+               set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
                actual = tty->ops->write(tty, tbuf->buf, tbuf->count);
 
                /* rollback was possible and has been done */
@@ -459,7 +459,7 @@ static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)
        }
        
        if (!tbuf)
-               tty->flags  &= ~(1 << TTY_DO_WRITE_WAKEUP);
+               clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
        
        /* Clear the re-entry flag */
        spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
@@ -491,7 +491,7 @@ static void n_hdlc_tty_wakeup(struct tty_struct *tty)
                return;
 
        if (tty != n_hdlc->tty) {
-               tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
+               clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
                return;
        }