4.9-stable review patch. If anyone has any objections, please let me know.

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From: John Stultz john.stultz@linaro.org

[ Upstream commit 1416270f4a1ae83ea84156ceba19a66a8f88be1f ]

In the past we've warned when ADJ_OFFSET was in progress, usually caused by ntpd or some other time adjusting daemon running in non steady sate, which can cause the skew calculations to be incorrect.

Thus, this patch checks to see if the clock was being adjusted when we fail so that we don't cause false negatives.

Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@kernel.org Cc: Miroslav Lichvar mlichvar@redhat.com Cc: Richard Cochran richardcochran@gmail.com Cc: Prarit Bhargava prarit@redhat.com Cc: Stephen Boyd sboyd@kernel.org Cc: Shuah Khan shuah@kernel.org Cc: linux-kselftest@vger.kernel.org Suggested-by: Miroslav Lichvar mlichvar@redhat.com Signed-off-by: John Stultz john.stultz@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- v2: Widened the checks to look for other clock adjustments that could happen, as suggested by Miroslav v3: Fixed up commit message Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/testing/selftests/timers/raw_skew.c | 5 +++++ 1 file changed, 5 insertions(+)

--- a/tools/testing/selftests/timers/raw_skew.c +++ b/tools/testing/selftests/timers/raw_skew.c @@ -146,6 +146,11 @@ int main(int argv, char **argc) printf(" %lld.%i(act)", ppm/1000, abs((int)(ppm%1000)));

if (llabs(eppm - ppm) > 1000) { + if (tx1.offset || tx2.offset || + tx1.freq != tx2.freq || tx1.tick != tx2.tick) { + printf(" [SKIP]\n"); + return ksft_exit_skip("The clock was adjusted externally. Shutdown NTPd or other time sync daemons\n"); + } printf(" [FAILED]\n"); return ksft_exit_fail(); }