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SubjectRe: [RFC] Fast assurate clock readable from user space and NMI handler
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On Tue, 2007-02-27 at 14:04 -0500, Mathieu Desnoyers wrote:
> __get_nsec_offset : reads clock->cycle_last. Should be called with
> xtime_lock held. (ok so far, but see below)
>
> change_clocksource
> clock->cycle_last = now; (non atomic 64 bits update. Not protected by
> any lock ?) -> this would race with __get_nsec_offset ?

Minor nit (it could probably use a comment fixup): its only called from
update_wall_time, which holds xtime_lock.

> update_wall_time
> Called from timer interrupt. Holds xtime_lock and has a priority higher
> than other interrupts. Other clock->cycle_last protected by
> write_seqlock_irqsave.

-john

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