1 files changed, 17 insertions, 11 deletions

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 7fbad56db7c9..e3a9321f7f89 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1468,14 +1468,14 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
          * mode.  We don't want to throttle the driver if we're in
          * canonical mode and don't have a newline yet!
          */
-        if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
-                tty_throttle(tty);
-
-        /* FIXME: there is a tiny race here if the receive room check runs
-           before the other work executes and empties the buffer (upping
-           the receiving room and unthrottling. We then throttle and get
-           stuck. This has been observed and traced down by Vincent Pillet/
-           We need to address this when we sort out out the rx path locking */
+        while (1) {
+                tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
+                if (tty->receive_room >= TTY_THRESHOLD_THROTTLE)
+                        break;
+                if (!tty_throttle_safe(tty))
+                        break;
+        }
+        __tty_set_flow_change(tty, 0);
 }
 
 int is_ignored(int sig)
@@ -1944,11 +1944,17 @@ do_it_again:
                  * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
                  * we won't get any more characters.
                  */
-                if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
+                while (1) {
+                        tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
+                        if (n_tty_chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
+                                break;
+                        if (!tty->count)
+                                break;
                         n_tty_set_room(tty);
-                        if (tty->count)
-                                tty_unthrottle(tty);
+                        if (!tty_unthrottle_safe(tty))
+                                break;
                 }
+                __tty_set_flow_change(tty, 0);
 
                 if (b - buf >= minimum)
                         break;