From: Stanislav Kinsbursky <skinsbursky@parallels.com>
To: "Myklebust, Trond" <Trond.Myklebust@netapp.com>
Cc: "Schumaker, Bryan" <Bryan.Schumaker@netapp.com>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
Pavel Emelianov <xemul@parallels.com>,
"neilb@suse.de" <neilb@suse.de>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"bfields@fieldses.org" <bfields@fieldses.org>,
"davem@davemloft.net" <davem@davemloft.net>
Subject: Re: [PATCH v4 1/8] SUNRPC: introduce helpers for reference counted rpcbind clients
Date: Tue, 20 Sep 2011 19:03:37 +0400 [thread overview]
Message-ID: <4E78AB49.1030303@parallels.com> (raw)
In-Reply-To: <2E1EB2CF9ED1CB4AA966F0EB76EAB4430B47FD2B@SACMVEXC2-PRD.hq.netapp.com>
20.09.2011 18:38, Myklebust, Trond пишет:
>> -----Original Message-----
>> From: Stanislav Kinsbursky [mailto:skinsbursky@parallels.com]
>> Sent: Tuesday, September 20, 2011 10:35 AM
>> To: Myklebust, Trond
>> Cc: Schumaker, Bryan; linux-nfs@vger.kernel.org; Pavel Emelianov;
>> neilb@suse.de; netdev@vger.kernel.org; linux-kernel@vger.kernel.org;
>> bfields@fieldses.org; davem@davemloft.net
>> Subject: Re: [PATCH v4 1/8] SUNRPC: introduce helpers for reference
>> counted rpcbind clients
>>
>> 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?
>
> Yes, and so you don't need an smp_rmb() on the reader side. However, you still need to ensure that the processor which _sets_ the rpcb_users and rpcb_local_clnt/4 actually writes them in the correct order.
>
Yep, now I understand what are you talking about.
Will fix both places (set and put).
--
Best regards,
Stanislav Kinsbursky
next prev parent reply other threads:[~2011-09-20 15:04 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-20 10:13 [PATCH v4 0/8] SUNRPC: make rpcbind clients allocated and destroyed dynamically Stanislav Kinsbursky
2011-09-20 10:13 ` [PATCH v4 1/8] SUNRPC: introduce helpers for reference counted rpcbind clients Stanislav Kinsbursky
2011-09-20 13:05 ` Bryan Schumaker
2011-09-20 13:15 ` Myklebust, Trond
2011-09-20 13:34 ` Stanislav Kinsbursky
2011-09-20 14:14 ` Myklebust, Trond
2011-09-20 14:35 ` Stanislav Kinsbursky
2011-09-20 14:38 ` Myklebust, Trond
2011-09-20 15:03 ` Stanislav Kinsbursky [this message]
2011-09-20 16:20 ` Stanislav Kinsbursky
2011-09-20 17:13 ` Myklebust, Trond
2011-09-20 17:26 ` Stanislav Kinsbursky
2011-09-20 13:49 ` [PATCH v5 " Stanislav Kinsbursky
2011-09-20 14:24 ` Jeff Layton
2011-09-20 14:41 ` Myklebust, Trond
2011-09-20 15:58 ` Stanislav Kinsbursky
2011-09-20 14:43 ` Stanislav Kinsbursky
2011-09-20 14:58 ` Bryan Schumaker
2011-09-20 15:38 ` Stanislav Kinsbursky
2011-09-20 16:06 ` Bryan Schumaker
2011-09-20 15:11 ` Jeff Layton
2011-09-20 16:20 ` Stanislav Kinsbursky
2011-09-21 9:07 ` [PATCH v6 " Stanislav Kinsbursky
2011-09-23 14:41 ` Stanislav Kinsbursky
2011-09-23 17:26 ` Myklebust, Trond
2011-09-20 10:13 ` [PATCH v4 2/8] SUNRPC: use rpcbind reference counting helpers Stanislav Kinsbursky
2011-09-20 10:13 ` [PATCH v4 3/8] SUNRPC: introduce svc helpers for prepairing rpcbind infrastructure Stanislav Kinsbursky
2011-09-20 10:14 ` [PATCH v4 4/8] SUNRPC: setup rpcbind clients if service requires it Stanislav Kinsbursky
2011-09-20 11:22 ` Jeff Layton
2011-09-20 10:14 ` [PATCH v4 5/8] SUNRPC: cleanup service destruction Stanislav Kinsbursky
2011-09-20 10:14 ` [PATCH v4 6/8] NFSd: call svc rpcbind cleanup explicitly Stanislav Kinsbursky
2011-09-20 10:14 ` [PATCH v4 7/8] SUNRPC: remove rpcbind clients creation during service registering Stanislav Kinsbursky
2011-09-20 10:14 ` [PATCH v4 8/8] SUNRPC: remove rpcbind clients destruction on module cleanup Stanislav Kinsbursky
2011-09-20 11:24 ` [PATCH v4 0/8] SUNRPC: make rpcbind clients allocated and destroyed dynamically Jeff Layton
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