# Re: \[PATCH v4 1/8\] SUNRPC: introduce helpers for reference counted rpcbind clients

- From: Stanislav Kinsbursky \<hidden\>
- Date: 2011-09-20 14:35:51 
- List: netdev
- Page: https://ratatoskr.run/netdev/2011/09/3765411
- Thread: https://ratatoskr.run/linux-nfs/2011/09/3765270/t.md

```text
20.09.2011 18:14, Myklebust, Trond пишет:

>>>
>>> Doesn't it  need to be protected by rpcb_clnt_lock too?
>>>
>>
>> Nope from my pow. It's protected by rpcb_create_local_mutex. I.e. no one
>> will change rpcb_users since it's zero. If it's non zero - we willn't get to
>> rpcb_set_local().
>
> OK, so you are saying that the rpcb_users++ below could be replaced by rpcb_users=1?
>

Yes, you right.

> In that case, don't you need a smp_wmb() between the setting of rpcb_local_clnt/4 and the setting of rpcb_users? Otherwise, how do you guarantee that rpcb_users != 0 implies rpbc_local_clnt/4 != NULL?
>

We check rpcb_users under spinlock. Gain spinlock forces memory barrier, doesn't it?

-- 
Best regards,
Stanislav Kinsbursky
```