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Re: evtchn_do_event: handler...didn't lower ipl (Was: Re: xl or xm for xen)

On Tue, Dec 03, 2013 at 08:55:06AM +0700, Robert Elz wrote:
> When statclock() - and hardclock() before it - is (or are) called, the
> cpu (apparently) already holds a (spin) mutex (the ci_mtx_count field of
> the cpu_info struct is -1).    Given that, and the way spin mutexes work,
> statclock() (and then hardclock()) must return with the ipl higher.

I'd have thought that acquiring a mutex would increase the count.
So a count of -1 would indicate and extra release.
Or does this counter have silly values?


David Laight:

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