[PATCH v1 net-next 2/2] mptcp: Don't call tcp_update_recv_tstamps() if not needed.

[Kuniyuki Iwashima <kuniyu@google.com>]

As with TCP, __mptcp_recvmsg_mskq() also always triggers
tcp_recv_timestamp() if skb has hwtstamp.

Accessing sk->sk_tsflags incurs unnecessary costs for sockets
that do not need RX tstamp.

Let's check SOCK_RCVTSTAMP and SOCK_TIMESTAMPING_ANY under
lock_sock().

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
 net/mptcp/protocol.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 7a22e9388e0e..e632c7de779f 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2189,7 +2189,8 @@ static int __mptcp_recvmsg_mskq(struct sock *sk, struct msghdr *msg,
 			}
 		}
 
-		if (MPTCP_SKB_CB(skb)->has_rxtstamp) {
+		if (MPTCP_SKB_CB(skb)->has_rxtstamp &&
+		    sk_want_rx_tstamps(sk)) {
 			tcp_update_recv_tstamps(skb, tss);
 			*cmsg_flags |= MPTCP_CMSG_TS;
 		}
-- 
2.56.0.385.gac671c819a-goog