From 78fa74a23b16bdb0d944272b696915c4e0bb3ee1 Mon Sep 17 00:00:00 2001 From: George Anzinger Date: Thu, 28 Jul 2005 21:16:16 -0700 Subject: [PATCH] [PATCH] posix timers: fix normalization problem (We found this (after a customer complained) and it is in the kernel.org kernel. Seems that for CLOCK_MONOTONIC absolute timers and clock_nanosleep calls both the request time and wall_to_monotonic are subtracted prior to the normalize resulting in an overflow in the existing normalize test. This causes the result to be shifted ~4 seconds ahead instead of ~2 seconds back in time.) The normalize code in posix-timers.c fails when the tv_nsec member is ~1.2 seconds negative. This can happen on absolute timers (and clock_nanosleeps) requested on CLOCK_MONOTONIC (both the request time and wall_to_monotonic are subtracted resulting in the possibility of a number close to -2 seconds.) This fix uses the set_normalized_timespec() (which does not have an overflow problem) to fix the problem and as a side effect makes the code cleaner. Signed-off-by: George Anzinger Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/posix-timers.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-) diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 5b7b4736d82b..10b2ad749d14 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -896,21 +896,10 @@ static int adjust_abs_time(struct k_clock *clock, struct timespec *tp, jiffies_64_f = get_jiffies_64(); } /* - * Take away now to get delta + * Take away now to get delta and normalize */ - oc.tv_sec -= now.tv_sec; - oc.tv_nsec -= now.tv_nsec; - /* - * Normalize... - */ - while ((oc.tv_nsec - NSEC_PER_SEC) >= 0) { - oc.tv_nsec -= NSEC_PER_SEC; - oc.tv_sec++; - } - while ((oc.tv_nsec) < 0) { - oc.tv_nsec += NSEC_PER_SEC; - oc.tv_sec--; - } + set_normalized_timespec(&oc, oc.tv_sec - now.tv_sec, + oc.tv_nsec - now.tv_nsec); }else{ jiffies_64_f = get_jiffies_64(); } -- 2.20.1