From: Stanislav Kinsbursky <skinsbursky-bzQdu9zFT3WakBO8gow8eQ@public•gmane.org>
To: Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public•gmane.org>
Cc: "Trond.Myklebust-HgOvQuBEEgTQT0dZR+AlfA@public•gmane.org"
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<davem-fT/PcQaiUtIeIZ0/mPfg9Q@public•gmane.org>
Subject: Re: [PATCH v5 1/8] SUNRPC: introduce helpers for reference counted rpcbind clients
Date: Tue, 20 Sep 2011 18:43:45 +0400 [thread overview]
Message-ID: <4E78A6A1.1000800@parallels.com> (raw)
In-Reply-To: <20110920102431.58ca1d96-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org>
20.09.2011 18:24, Jeff Layton пишет:
> On Tue, 20 Sep 2011 17:49:27 +0400
> Stanislav Kinsbursky<skinsbursky-bzQdu9zFT3WakBO8gow8eQ@public•gmane.org> wrote:
>
>> v5: fixed races with rpcb_users in rpcb_get_local()
>>
>> This helpers will be used for dynamical creation and destruction of rpcbind
>> clients.
>> Variable rpcb_users is actually a counter of lauched RPC services. If rpcbind
>> clients has been created already, then we just increase rpcb_users.
>>
>> Signed-off-by: Stanislav Kinsbursky<skinsbursky-bzQdu9zFT3WakBO8gow8eQ@public•gmane.org>
>>
>> ---
>> net/sunrpc/rpcb_clnt.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 files changed, 53 insertions(+), 0 deletions(-)
>>
>> diff --git a/net/sunrpc/rpcb_clnt.c b/net/sunrpc/rpcb_clnt.c
>> index e45d2fb..5f4a406 100644
>> --- a/net/sunrpc/rpcb_clnt.c
>> +++ b/net/sunrpc/rpcb_clnt.c
>> @@ -114,6 +114,9 @@ static struct rpc_program rpcb_program;
>> static struct rpc_clnt * rpcb_local_clnt;
>> static struct rpc_clnt * rpcb_local_clnt4;
>> +DEFINE_SPINLOCK(rpcb_clnt_lock);
>> +unsigned int rpcb_users;
>> +
>> struct rpcbind_args {
>> struct rpc_xprt * r_xprt;
>> @@ -161,6 +164,56 @@ static void rpcb_map_release(void *data)
>> kfree(map);
>> }
>> +static int rpcb_get_local(void)
>> +{
>> + int cnt;
>> +
>> + spin_lock(&rpcb_clnt_lock);
>> + if (rpcb_users)
>> + rpcb_users++;
>> + cnt = rpcb_users;
>> + spin_unlock(&rpcb_clnt_lock);
>> +
>> + return cnt;
>> +}
>> +
>> +void rpcb_put_local(void)
>> +{
>> + struct rpc_clnt *clnt = rpcb_local_clnt;
>> + struct rpc_clnt *clnt4 = rpcb_local_clnt4;
>> + int shutdown;
>> +
>> + spin_lock(&rpcb_clnt_lock);
>> + if (--rpcb_users == 0) {
>> + rpcb_local_clnt = NULL;
>> + rpcb_local_clnt4 = NULL;
>> + }
>
> In the function below, you mention that the above pointers are
> protected by rpcb_create_local_mutex, but it looks like they get reset
> here without that being held?
>
Assigning of them is protected by rpcb_create_local_mutex.
Dereferencing of them is protected by rpcb_clnt_lock.
> Might it be simpler to just protect rpcb_users with the
> rpcb_create_local_mutex and ensure that it's held whenever you call one
> of these routines? None of these are codepaths are particularly hot.
>
I just inherited this lock-mutex logic.
Actually, you right. This codepaths are used rarely.
But are use sure, that we need to remove this "speed-up" logic if we take into
account that it was here already?
>> + shutdown = !rpcb_users;
>> + spin_unlock(&rpcb_clnt_lock);
>> +
>> + if (shutdown) {
>> + /*
>> + * cleanup_rpcb_clnt - remove xprtsock's sysctls, unregister
>> + */
>> + if (clnt4)
>> + rpc_shutdown_client(clnt4);
>> + if (clnt)
>> + rpc_shutdown_client(clnt);
>> + }
>> + return;
>> +}
>> +
>> +static void rpcb_set_local(struct rpc_clnt *clnt, struct rpc_clnt *clnt4)
>> +{
>> + /* Protected by rpcb_create_local_mutex */
>> + rpcb_local_clnt = clnt;
>> + rpcb_local_clnt4 = clnt4;
>> + rpcb_users++;
>> + dprintk("RPC: created new rpcb local clients (rpcb_local_clnt: "
>> + "%p, rpcb_local_clnt4: %p)\n", rpcb_local_clnt,
>> + rpcb_local_clnt4);
>> +}
>> +
>> /*
>> * Returns zero on success, otherwise a negative errno value
>> * is returned.
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public•gmane.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
>
--
Best regards,
Stanislav Kinsbursky
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next prev parent reply other threads:[~2011-09-20 14:43 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
[not found] ` <4E789679.1060601-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
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
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
[not found] ` <20110920102431.58ca1d96-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org>
2011-09-20 14:43 ` Stanislav Kinsbursky [this message]
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
[not found] ` <20110920101404.9861.83097.stgit-bi+AKbBUZKagILUCTcTcHdKyNwTtLsGr@public.gmane.org>
2011-09-20 11:22 ` Jeff Layton
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
[not found] ` <20110920101031.9861.18444.stgit-bi+AKbBUZKagILUCTcTcHdKyNwTtLsGr@public.gmane.org>
2011-09-20 10:14 ` [PATCH v4 5/8] SUNRPC: cleanup service destruction 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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