Messages in this thread | | | Date | Thu, 9 Dec 2021 20:50:38 +0800 | Subject | Re: [PATCH] time: Normalize timespec64 before timespec64_compare() | From | Yu Liao <> |
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Is there any comments about this patch? BTW, is it necessary to add set_normalized_timespec64 to timespec64_compare?
Thanks, Yu
On 2021/12/2 21:07, Yu Liao wrote: > Passing unnormalized timespec64 to timespec64_compare() may cause > incorrect results. > > For example: > wall_to_monotonic = {tv_sec = -10, tv_nsec = 900000000} > ts_delta = {tv_sec = -9, tv_nsec = -900000000} > > timespec64_compare() returns -1, but actually wall_to_monotonic > ts_delta. > This will cause wall_to_monotonic to become a positive number. > > Use timespec64_sub() instead of direct subtraction to avoid this. > > Signed-off-by: Yu Liao <liaoyu15@huawei.com> > --- > include/linux/time64.h | 2 ++ > kernel/time/timekeeping.c | 3 +-- > 2 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/include/linux/time64.h b/include/linux/time64.h > index 81b9686a2079..f74a36d253cd 100644 > --- a/include/linux/time64.h > +++ b/include/linux/time64.h > @@ -50,6 +50,8 @@ static inline int timespec64_equal(const struct timespec64 *a, > * lhs < rhs: return <0 > * lhs == rhs: return 0 > * lhs > rhs: return >0 > + * > + * Note: Both lhs and rhs must be normalized. > */ > static inline int timespec64_compare(const struct timespec64 *lhs, const struct timespec64 *rhs) > { > diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c > index b348749a9fc6..dcdcb85121e4 100644 > --- a/kernel/time/timekeeping.c > +++ b/kernel/time/timekeeping.c > @@ -1306,8 +1306,7 @@ int do_settimeofday64(const struct timespec64 *ts) > timekeeping_forward_now(tk); > > xt = tk_xtime(tk); > - ts_delta.tv_sec = ts->tv_sec - xt.tv_sec; > - ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec; > + ts_delta = timespec64_sub(*ts, xt); > > if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) { > ret = -EINVAL;
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