[PATCH v2 mptcp-next 1/8] mptcp: enable busypoll from mptcp receive path

[Florian Westphal <fw@strlen.de>]

The setting is only relevant for the msk socket.
While at it, also handle rcvlowat/rcvtimeo this way.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/mptcp/protocol.c | 7 +++++++
 net/mptcp/sockopt.c  | 8 ++++++++
 2 files changed, 15 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 652e55a0c6e8..86e599eb4403 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -12,6 +12,7 @@
 #include <linux/sched/signal.h>
 #include <linux/atomic.h>
 #include <net/sock.h>
+#include <net/busy_poll.h>
 #include <net/inet_common.h>
 #include <net/inet_hashtables.h>
 #include <net/protocol.h>
@@ -1982,6 +1983,12 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 	if (unlikely(flags & MSG_ERRQUEUE))
 		return inet_recv_error(sk, msg, len, addr_len);
 
+	if (sk_can_busy_loop(sk) &&
+	    skb_queue_empty_lockless(&msk->receive_queue) &&
+	    skb_queue_empty_lockless(&sk->sk_receive_queue) &&
+	    inet_sk_state_load(sk) == TCP_ESTABLISHED)
+		sk_busy_loop(sk, nonblock);
+
 	mptcp_lock_sock(sk, __mptcp_splice_receive_queue(sk));
 	if (unlikely(sk->sk_state == TCP_LISTEN)) {
 		copied = -ENOTCONN;
diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index a79798189599..ee55e4145d7e 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -254,6 +254,14 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,
 		return mptcp_setsockopt_sol_socket_int(msk, optname, optval, optlen);
 	case SO_LINGER:
 		return mptcp_setsockopt_sol_socket_linger(msk, optval, optlen);
+	case SO_RCVLOWAT:
+	case SO_RCVTIMEO_OLD:
+	case SO_RCVTIMEO_NEW:
+	case SO_BUSY_POLL:
+	case SO_PREFER_BUSY_POLL:
+	case SO_BUSY_POLL_BUDGET:
+		/* No need to copy: only relevant for msk */
+		break;
 	case SO_NO_CHECK:
 	case SO_DONTROUTE:
 	case SO_BROADCAST:
-- 
2.26.3