Re: [PATCH v6 1/8] SUNRPC: introduce helpers for reference counted rpcbind clients

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25.10.2011 15:16, Trond Myklebust пишет:
On Tue, 2011-10-25 at 14:16 +0300, Stanislav Kinsbursky wrote:
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<skinsbursky@xxxxxxxxxxxxx>

---
  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;

I'm removing this before applying...

Sorry, but I don't understand what exactly you are removing, and why?

+}
+



--
Best regards,
Stanislav Kinsbursky
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