Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:44734 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750784Ab1ITOYn (ORCPT ); Tue, 20 Sep 2011 10:24:43 -0400 Date: Tue, 20 Sep 2011 10:24:31 -0400 From: Jeff Layton To: Stanislav Kinsbursky Cc: "Trond.Myklebust@netapp.com" , "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 v5 1/8] SUNRPC: introduce helpers for reference counted rpcbind clients Message-ID: <20110920102431.58ca1d96@tlielax.poochiereds.net> In-Reply-To: <4E7899E7.9090809@parallels.com> References: <20110920101031.9861.18444.stgit@localhost6.localdomain6> <20110920101341.9861.51453.stgit@localhost6.localdomain6> <4E7899E7.9090809@parallels.com> Content-Type: text/plain; charset=US-ASCII Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Tue, 20 Sep 2011 17:49:27 +0400 Stanislav Kinsbursky 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 > > --- > 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? 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. > + 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@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Jeff Layton