Re: [PATCH 23/32] Generic dynamic per cpu refcounting

[Rusty Russell]

Tejun Heo <tj@xxxxxxxxxx> writes:
>> It also implements two stage shutdown, as we need it to tear down the
>> percpu counts. Before dropping the initial refcount, you must call
>> percpu_ref_kill(); this puts the refcount in "shutting down mode" and
>> switches back to a single atomic refcount with the appropriate barriers
>> (synchronize_rcu()).
>
> Maybe if we have tryget() which only succeeds if the counter is alive,
> we can replace moulde refcnt with this?  Rusty?

Yes, it's similar (hence my previous interest), though module count is a
bit weird.

Like Tejun, I'd prefer to see it always alloc up-front, because it
avoids the _noalloc variant (which is backwards: please hand gfp_t, so
you don't hide the alloc) and heuristics.

Cheers,
Rusty.
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