NFSd: call rpc_destroy_wait_queue() from free_client()

commit 4cb57e30 upstream.

Mainly to ensure that we don't leave any hanging timers.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

fs/nfsd/nfs4state.c

@@ -1011,6 +1011,7 @@ free_client(struct nfs4_client *clp)
 		list_del(&ses->se_perclnt);
 		nfsd4_put_session(ses);
 	}
+	rpc_destroy_wait_queue(&clp->cl_cb_waitq);
 	if (clp->cl_cred.cr_group_info)
 		put_group_info(clp->cl_cred.cr_group_info);
 	kfree(clp->cl_principal);