diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index ee1c268..54d1fc5 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1832,13 +1832,13 @@ do_it_again:
 
 		if (tty->icanon && !L_EXTPROC(tty)) {
 			/* N.B. avoid overrun if nr == 0 */
+			spin_lock_irqsave(&tty->read_lock, flags);
 			while (nr && tty->read_cnt) {
 				int eol;
 
 				eol = test_and_clear_bit(tty->read_tail,
 						tty->read_flags);
 				c = tty->read_buf[tty->read_tail];
-				spin_lock_irqsave(&tty->read_lock, flags);
 				tty->read_tail = ((tty->read_tail+1) &
 						  (N_TTY_BUF_SIZE-1));
 				tty->read_cnt--;
@@ -1864,6 +1864,7 @@ do_it_again:
 					tty_audit_push(tty);
 					break;
 				}
+				spin_lock_irqsave(&tty->read_lock, flags);
 			}
 			if (retval)
 				break;