SUNRPC: Micro optimisation for svc_data_ready

Don't call svc_xprt_enqueue() if the XPT_DATA flag is already set.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

net/sunrpc/svcsock.c

@@ -409,8 +409,8 @@ static void svc_data_ready(struct sock *sk)
 			svsk, sk,
 			test_bit(XPT_BUSY, &svsk->sk_xprt.xpt_flags));
 		svsk->sk_odata(sk);
-		set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);
-		svc_xprt_enqueue(&svsk->sk_xprt);
+		if (!test_and_set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags))
+			svc_xprt_enqueue(&svsk->sk_xprt);
 	}
 }