From: Arnd Bergmann <arnd@arndb.de>
Date: Mon, 25 Nov 2019 20:25:46 +0000 (+0100)
Subject: y2038: alarm: fix half-second cut-off
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=b111df8447acdeb4b9220f99d5d4b28f83eb56ad;p=linux.git

y2038: alarm: fix half-second cut-off

Changing alarm_itimer accidentally broke the logic for arithmetic
rounding of half seconds in the return code.

Change it to a constant based on NSEC_PER_SEC, as suggested by
Ben Hutchings.

Fixes: bd40a175769d ("y2038: itimer: change implementation to timespec64")
Reported-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---

diff --git a/kernel/time/itimer.c b/kernel/time/itimer.c
index 5872db9bd5f76..9e59c9ea92aa6 100644
--- a/kernel/time/itimer.c
+++ b/kernel/time/itimer.c
@@ -297,7 +297,7 @@ static unsigned int alarm_setitimer(unsigned int seconds)
 	 * better return too much than too little anyway
 	 */
 	if ((!it_old.it_value.tv_sec && it_old.it_value.tv_nsec) ||
-	      it_old.it_value.tv_nsec >= 500000)
+	      it_old.it_value.tv_nsec >= (NSEC_PER_SEC / 2))
 		it_old.it_value.tv_sec++;
 
 	return it_old.it_value.tv_sec;