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SubjectRe: [PATCH 1/4] lockd: convert nlm_host.h_count from atomic_t to refcount_t
On Fri, Dec 22, 2017 at 09:29:15AM +0000, Reshetova, Elena wrote:
>
> On Wed, Nov 29, 2017 at 01:15:43PM +0200, Elena Reshetova wrote:
> > atomic_t variables are currently used to implement reference
> > counters with the following properties:
> > - counter is initialized to 1 using atomic_set()
> > - a resource is freed upon counter reaching zero
> > - once counter reaches zero, its further
> > increments aren't allowed
> > - counter schema uses basic atomic operations
> > (set, inc, inc_not_zero, dec_and_test, etc.)
>
> >Whoops, I forgot that this doesn't apply to h_count.
>
> >Well, it's confusing, because h_count is actually used in two different
> >ways: depending on whether a nlm_host represents a client or server, it
> >may have the above properties or not.
>
>
> So, what happens when it is not having the above properties? Is the object
> being reused or?

The object isn't destroyed when the counter hits zero--zero is just
taken as a hint to some garbage collection algorithm that it would be OK
to destroy it. So decrementing to or incrementing from zero is OK.

--b.

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