From 2446ab6070861aba2dd9229463ffbc40016a9f33 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Thu, 1 Mar 2012 17:00:56 -0500 Subject: SUNRPC: Use RCU to dereference the rpc_clnt.cl_xprt field A migration event will replace the rpc_xprt used by an rpc_clnt. To ensure this can be done safely, all references to cl_xprt must now use a form of rcu_dereference(). Special care is taken with rpc_peeraddr2str(), which returns a pointer to memory whose lifetime is the same as the rpc_xprt. Signed-off-by: Trond Myklebust [ cel: fix lockdep splats and layering violations ] [ cel: forward ported to 3.4 ] [ cel: remove rpc_max_reqs(), add rpc_net_ns() ] Signed-off-by: Chuck Lever Signed-off-by: Trond Myklebust --- net/sunrpc/rpcb_clnt.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) (limited to 'net/sunrpc/rpcb_clnt.c') diff --git a/net/sunrpc/rpcb_clnt.c b/net/sunrpc/rpcb_clnt.c index b1f08bd67883..4f8af63798a2 100644 --- a/net/sunrpc/rpcb_clnt.c +++ b/net/sunrpc/rpcb_clnt.c @@ -620,9 +620,10 @@ static struct rpc_task *rpcb_call_async(struct rpc_clnt *rpcb_clnt, struct rpcbi static struct rpc_clnt *rpcb_find_transport_owner(struct rpc_clnt *clnt) { struct rpc_clnt *parent = clnt->cl_parent; + struct rpc_xprt *xprt = rcu_dereference(clnt->cl_xprt); while (parent != clnt) { - if (parent->cl_xprt != clnt->cl_xprt) + if (rcu_dereference(parent->cl_xprt) != xprt) break; if (clnt->cl_autobind) break; @@ -653,8 +654,12 @@ void rpcb_getport_async(struct rpc_task *task) size_t salen; int status; - clnt = rpcb_find_transport_owner(task->tk_client); - xprt = clnt->cl_xprt; + rcu_read_lock(); + do { + clnt = rpcb_find_transport_owner(task->tk_client); + xprt = xprt_get(rcu_dereference(clnt->cl_xprt)); + } while (xprt == NULL); + rcu_read_unlock(); dprintk("RPC: %5u %s(%s, %u, %u, %d)\n", task->tk_pid, __func__, @@ -667,6 +672,7 @@ void rpcb_getport_async(struct rpc_task *task) if (xprt_test_and_set_binding(xprt)) { dprintk("RPC: %5u %s: waiting for another binder\n", task->tk_pid, __func__); + xprt_put(xprt); return; } @@ -734,7 +740,7 @@ void rpcb_getport_async(struct rpc_task *task) switch (bind_version) { case RPCBVERS_4: case RPCBVERS_3: - map->r_netid = rpc_peeraddr2str(clnt, RPC_DISPLAY_NETID); + map->r_netid = xprt->address_strings[RPC_DISPLAY_NETID]; map->r_addr = rpc_sockaddr2uaddr(sap, GFP_ATOMIC); map->r_owner = ""; break; @@ -763,6 +769,7 @@ bailout_release_client: bailout_nofree: rpcb_wake_rpcbind_waiters(xprt, status); task->tk_status = status; + xprt_put(xprt); } EXPORT_SYMBOL_GPL(rpcb_getport_async); -- cgit v1.2.3