[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 <george@mvista.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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1 changed files with 3 additions and 14 deletions
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@ -896,21 +896,10 @@ static int adjust_abs_time(struct k_clock *clock, struct timespec *tp,
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jiffies_64_f = get_jiffies_64();
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jiffies_64_f = get_jiffies_64();
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}
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}
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/*
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/*
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* Take away now to get delta
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* Take away now to get delta and normalize
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*/
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*/
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oc.tv_sec -= now.tv_sec;
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set_normalized_timespec(&oc, oc.tv_sec - now.tv_sec,
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oc.tv_nsec -= now.tv_nsec;
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oc.tv_nsec - now.tv_nsec);
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/*
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* Normalize...
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*/
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while ((oc.tv_nsec - NSEC_PER_SEC) >= 0) {
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oc.tv_nsec -= NSEC_PER_SEC;
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oc.tv_sec++;
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}
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while ((oc.tv_nsec) < 0) {
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oc.tv_nsec += NSEC_PER_SEC;
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oc.tv_sec--;
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}
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}else{
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}else{
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jiffies_64_f = get_jiffies_64();
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jiffies_64_f = get_jiffies_64();
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}
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}
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