1 files changed, 37 insertions, 44 deletions

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 26f097f60b10..d2b496750d59 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -321,7 +321,8 @@ static void n_tty_check_unthrottle(struct tty_struct *tty)
 
 static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
 {
-        *read_buf_addr(ldata, ldata->read_head++) = c;
+        *read_buf_addr(ldata, ldata->read_head) = c;
+        ldata->read_head++;
 }
 
 /**
@@ -351,13 +352,13 @@ static void n_tty_packet_mode_flush(struct tty_struct *tty)
 {
         unsigned long flags;
 
-        spin_lock_irqsave(&tty->ctrl_lock, flags);
         if (tty->link->packet) {
+                spin_lock_irqsave(&tty->ctrl_lock, flags);
                 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
+                spin_unlock_irqrestore(&tty->ctrl_lock, flags);
                 if (waitqueue_active(&tty->link->read_wait))
                         wake_up_interruptible(&tty->link->read_wait);
         }
-        spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 }
 
 /**
@@ -2128,7 +2129,6 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
         int minimum, time;
         ssize_t retval = 0;
         long timeout;
-        unsigned long flags;
         int packet;
 
         c = job_control(tty, file);
@@ -2174,10 +2174,10 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
                         unsigned char cs;
                         if (b != buf)
                                 break;
-                        spin_lock_irqsave(&tty->link->ctrl_lock, flags);
+                        spin_lock_irq(&tty->link->ctrl_lock);
                         cs = tty->link->ctrl_status;
                         tty->link->ctrl_status = 0;
-                        spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
+                        spin_unlock_irq(&tty->link->ctrl_lock);
                         if (tty_put_user(tty, cs, b++)) {
                                 retval = -EFAULT;
                                 b--;
@@ -2193,45 +2193,29 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 
                 if (!input_available_p(tty, 0)) {
                         if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
-                                up_read(&tty->termios_rwsem);
-                                tty_flush_to_ldisc(tty);
-                                down_read(&tty->termios_rwsem);
-                                if (!input_available_p(tty, 0)) {
-                                        retval = -EIO;
-                                        break;
-                                }
-                        } else {
-                                if (tty_hung_up_p(file))
-                                        break;
-                                if (!timeout)
-                                        break;
-                                if (file->f_flags & O_NONBLOCK) {
-                                        retval = -EAGAIN;
-                                        break;
-                                }
-                                if (signal_pending(current)) {
-                                        retval = -ERESTARTSYS;
-                                        break;
-                                }
-                                n_tty_set_room(tty);
-                                up_read(&tty->termios_rwsem);
-
-                                timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
-                                                     timeout);
-
-                                down_read(&tty->termios_rwsem);
-                                continue;
+                                retval = -EIO;
+                                break;
                         }
-                }
-
-                /* Deal with packet mode. */
-                if (packet && b == buf) {
-                        if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
-                                retval = -EFAULT;
-                                b--;
+                        if (tty_hung_up_p(file))
+                                break;
+                        if (!timeout)
+                                break;
+                        if (file->f_flags & O_NONBLOCK) {
+                                retval = -EAGAIN;
                                 break;
                         }
-                        nr--;
+                        if (signal_pending(current)) {
+                                retval = -ERESTARTSYS;
+                                break;
+                        }
+                        n_tty_set_room(tty);
+                        up_read(&tty->termios_rwsem);
+
+                        timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
+                                             timeout);
+
+                        down_read(&tty->termios_rwsem);
+                        continue;
                 }
 
                 if (ldata->icanon && !L_EXTPROC(tty)) {
@@ -2243,8 +2227,17 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
                                 break;
                 } else {
                         int uncopied;
-                        /* The copy function takes the read lock and handles
-                           locking internally for this case */
+
+                        /* Deal with packet mode. */
+                        if (packet && b == buf) {
+                                if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
+                                        retval = -EFAULT;
+                                        b--;
+                                        break;
+                                }
+                                nr--;
+                        }
+
                         uncopied = copy_from_read_buf(tty, &b, &nr);
                         uncopied += copy_from_read_buf(tty, &b, &nr);
                         if (uncopied) {