LTP and commit e1d7ba8735551ed7 ("time: Always make sure wall_to_monotonic isn't positive")

LTP and commit e1d7ba8735551ed7 ("time: Always make sure wall_to_monotonic isn't positive")

[Mark Rutland]

Hi,

While testing v4.3-rc1 with the LTP, we spotted failures in a couple of
timekeeping tests, which seem to be a result of commit e1d7ba8735551ed7
("time: Always make sure wall_to_monotonic isn't positive").

In both cases this is because the new time would be before the boot
time, so I guess these are covered by the caveat at the end of the
commit message.

settimeofday01 [1] tries tries to settimeofday() with a timeval 100s and
100ns, while clock_gettime02 [2] tries to clock_settime to 1s and
100ns. Neither expect -EINVAL, and report failure with the new
behaviour.

While I don't know that any "real" software is affected, I thought I
should let you know.

Thanks,
Mark.

[1] https://github.com/linux-test-project/ltp/blob/20150903/testcases/kernel/syscalls/settimeofday/settimeofday01.c
[2] https://github.com/linux-test-project/ltp/blob/20150903/testcases/kernel/timers/clock_settime/clock_settime02.c

Re: LTP and commit e1d7ba8735551ed7 ("time: Always make sure wall_to_monotonic isn't positive")

[Cyril Hrubis]

Hi!
> While testing v4.3-rc1 with the LTP, we spotted failures in a couple of
> timekeeping tests, which seem to be a result of commit e1d7ba8735551ed7
> ("time: Always make sure wall_to_monotonic isn't positive").
> 
> In both cases this is because the new time would be before the boot
> time, so I guess these are covered by the caveat at the end of the
> commit message.
> 
> settimeofday01 [1] tries tries to settimeofday() with a timeval 100s and
> 100ns, while clock_gettime02 [2] tries to clock_settime to 1s and
> 100ns. Neither expect -EINVAL, and report failure with the new
> behaviour.
> 
> While I don't know that any "real" software is affected, I thought I
> should let you know.

Thanks for the report, we allready have patch for the first testcase on
the mailing list that initializes the the timeval value to current time
+ small amount. I will have a look at the second test as well.

> [1] https://github.com/linux-test-project/ltp/blob/20150903/testcases/kernel/syscalls/settimeofday/settimeofday01.c
> [2] https://github.com/linux-test-project/ltp/blob/20150903/testcases/kernel/timers/clock_settime/clock_settime02.c

-- 
Cyril Hrubis
chrubis@suse.cz

Re: [LTP] LTP and commit e1d7ba8735551ed7 ("time: Always make sure wall_to_monotonic isn't positive")

[Cyril Hrubis]

Hi!
> Thanks for the report, we allready have patch for the first testcase on
> the mailing list that initializes the the timeval value to current time
> + small amount. I will have a look at the second test as well.
> 
> > [1] https://github.com/linux-test-project/ltp/blob/20150903/testcases/kernel/syscalls/settimeofday/settimeofday01.c
> > [2] https://github.com/linux-test-project/ltp/blob/20150903/testcases/kernel/timers/clock_settime/clock_settime02.c

Both should be fixed in latest git.

-- 
Cyril Hrubis
chrubis@suse.cz