Re: [PATCH v5 1/8] SUNRPC: introduce helpers for reference counted rpcbind clients
flat view
From: Jeff Layton <hidden>
Date: 2011-09-20 14:24:44
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On Tue, 20 Sep 2011 17:49:27 +0400 Stanislav Kinsbursky [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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.
--
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