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 <Trond.Myklebust@netapp.com>
[ 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 <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index c1111a3..bae959e 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1037,19 +1037,28 @@
void nfs4_schedule_state_manager(struct nfs_client *clp)
{
struct task_struct *task;
+ char buf[INET6_ADDRSTRLEN + sizeof("-manager") + 1];
if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
return;
__module_get(THIS_MODULE);
atomic_inc(&clp->cl_count);
- task = kthread_run(nfs4_run_state_manager, clp, "%s-manager",
- rpc_peeraddr2str(clp->cl_rpcclient,
- RPC_DISPLAY_ADDR));
- if (!IS_ERR(task))
- return;
- nfs4_clear_state_manager_bit(clp);
- nfs_put_client(clp);
- module_put(THIS_MODULE);
+
+ /* The rcu_read_lock() is not strictly necessary, as the state
+ * manager is the only thread that ever changes the rpc_xprt
+ * after it's initialized. At this point, we're single threaded. */
+ rcu_read_lock();
+ snprintf(buf, sizeof(buf), "%s-manager",
+ rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));
+ rcu_read_unlock();
+ task = kthread_run(nfs4_run_state_manager, clp, buf);
+ if (IS_ERR(task)) {
+ printk(KERN_ERR "%s: kthread_run: %ld\n",
+ __func__, PTR_ERR(task));
+ nfs4_clear_state_manager_bit(clp);
+ nfs_put_client(clp);
+ module_put(THIS_MODULE);
+ }
}
/*