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Thomas Gleixner authored
The recent rework of the posix timer internals broke the magic posix mechanism, which requires that relative timers are not affected by modifications of the underlying clock. That means relative CLOCK_REALTIME timers cannot use CLOCK_REALTIME, because that can be set and adjusted. The underlying hrtimer switches the clock for these timers to CLOCK_MONOTONIC. That still works, but reading the remaining time of such a timer has been broken in the rework. The old code used the hrtimer internals directly and avoided the posix clock callbacks. Now common_timer_get() uses the underlying kclock->timer_get() callback, which is still CLOCK_REALTIME based. So the remaining time of such a timer is calculated against the wrong time base. Handle it by switching the k_itimer->kclock pointer according to the resulting hrtimer mode. k_itimer->it_clock still contains CLOCK_REALTIME because the timer might be set with ABSTIME later and then it needs to switch back to the realtime posix clock implementation. Fixes: eae1c4ae ("posix-timers: Make use of cancel/arm callbacks") Reported-by:
Andrei Vagin <avagin@virtuozzo.com> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Link: http://lkml.kernel.org/r/20170609201156.GB21491@outlook.office365.com
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