NFSd: call rpc_destroy_wait_queue() from free_client()

Mainly to ensure that we don't leave any hanging timers.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

(cherry picked from commit 4cb57e30)
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

fs/nfsd/nfs4state.c

@@ -1052,6 +1052,7 @@ free_client(struct nfs4_client *clp)
 		list_del(&ses->se_perclnt);
 		nfsd4_put_session_locked(ses);
 	}
+	rpc_destroy_wait_queue(&clp->cl_cb_waitq);
 	free_svc_cred(&clp->cl_cred);
 	kfree(clp->cl_name.data);
 	idr_remove_all(&clp->cl_stateids);