tty: n_tty: use time_is_before_jiffies() in n_tty_receive_overrun()

The jiffies tests in n_tty_receive_overrun() are simplified ratelimiting
(without locking). We could use struct ratelimit_state and the helpers,
but to me, it occurs to be too complex for this use case.

But the code currently tests both if the time passed (the first
time_after()) and if jiffies wrapped around (the second time_after()).
time_is_before_jiffies() takes care of both, provided overrun_time is
initialized at the allocation time.

So switch to time_is_before_jiffies(), the same what ratelimiting does.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Jiri Slaby (SUSE)

drivers/tty/n_tty.c

@@ -1173,8 +1173,7 @@ static void n_tty_receive_overrun(const struct tty_struct *tty)
 	struct n_tty_data *ldata = tty->disc_data;
 
 	ldata->num_overrun++;
-	if (time_after(jiffies, ldata->overrun_time + HZ) ||
-	    time_after(ldata->overrun_time, jiffies)) {
+	if (time_is_before_jiffies(ldata->overrun_time + HZ)) {
 		tty_warn(tty, "%d input overrun(s)\n", ldata->num_overrun);
 		ldata->overrun_time = jiffies;
 		ldata->num_overrun = 0;