From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stanislav Kinsbursky Subject: [PATCH v6 1/8] SUNRPC: introduce helpers for reference counted rpcbind clients Date: Tue, 25 Oct 2011 14:16:36 +0300 Message-ID: <20111025101608.12689.68689.stgit@localhost6.localdomain6> References: <20111025100826.12689.46944.stgit@localhost6.localdomain6> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: linux-nfs@vger.kernel.org, xemul@parallels.com, neilb@suse.de, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bfields@fieldses.org, davem@davemloft.net, devel@openvz.org To: Trond.Myklebust@netapp.com Return-path: In-Reply-To: <20111025100826.12689.46944.stgit@localhost6.localdomain6> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org v6: 1) added write memory barrier to rpcb_set_local to make sure, that rpcbind clients become valid before rpcb_users assignment 2) explicitly set rpcb_users to 1 instead of incrementing it (looks clearer from my pow). 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 | 54 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 54 insertions(+), 0 deletions(-) diff --git a/net/sunrpc/rpcb_clnt.c b/net/sunrpc/rpcb_clnt.c index e45d2fb..9fcdb42 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 +164,57 @@ 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; + } + 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; + smp_wmb(); + rpcb_users = 1; + 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.