# Re: \[RFC\]\[PATCH\] nfsd: add +1 to reference counting scheme for struct nfsd4\_session

- From: David Windsor \<hidden\>
- Date: 2017-02-13 11:42:56 
- List: netdev
- Page: https://ratatoskr.run/netdev/2017/02/11044912
- Thread: https://ratatoskr.run/linux-nfs/2017/02/11044912/t.md

```text
On Mon, Feb 13, 2017 at 5:38 AM, Christoph Hellwig [ref] wrote:
> On Sat, Feb 11, 2017 at 09:01:15AM -0500, David Windsor wrote:
>> I'm not sure there's another way to accomplish what we need
>> (initializing struct nfsd4_session objects with refcount=1) without
>> also modifying the freeable reference state.  After migrating to the
>> refcount_t API, if we leave init_session() as is, the first call to
>> nfsd4_get_session_locked() will fail:
>
> Which is a pretty clear indicator that this code should simply not
> migrate to the recount_t API.  Why was it even considered if the
> conversion is obviously broken?

I'm not sure this is a sound argument for not converting to
refcount_t.  In other locations in which refcounting schemes are
"unnatural," i.e. freeing refcounted objects when their refcount is -1
(rather than 0), conversion to refcount_t is accomplished by
performing a logical +1 to the overall refcounting scheme.  We're
auditing all refcounting corner cases, such as these, to see if
similar solutions can be found.

Thanks,
David
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