mptcp: cleanup MPJ subflow list handling

We can simplify the join list handling leveraging the
mptcp_release_cb(): if we can acquire the msk socket
lock at mptcp_finish_join time, move the new subflow
directly into the conn_list, otherwise place it on join_list and
let the release_cb process such list.

Since pending MPJ connection are now always processed
in a timely way, we can avoid flushing the join list
every time we have to process all the current subflows.

Additionally we can now use the mptcp data lock to protect
the join_list, removing the additional spin lock.

Finally, the MPJ handshake is now always finalized under the
msk socket lock, we can drop the additional synchronization
between mptcp_finish_join() and mptcp_close().

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 18 deletions

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index aa3fcd86dbe2..dacf3cee0027 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -1285,27 +1285,15 @@ void mptcp_sockopt_sync(struct mptcp_sock *msk, struct sock *ssk)
 	}
 }
 
-void mptcp_sockopt_sync_all(struct mptcp_sock *msk)
+void mptcp_sockopt_sync_locked(struct mptcp_sock *msk, struct sock *ssk)
 {
-	struct mptcp_subflow_context *subflow;
-	struct sock *sk = (struct sock *)msk;
-	u32 seq;
-
-	seq = sockopt_seq_reset(sk);
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 
-	mptcp_for_each_subflow(msk, subflow) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-		u32 sseq = READ_ONCE(subflow->setsockopt_seq);
+	msk_owned_by_me(msk);
 
-		if (sseq != msk->setsockopt_seq) {
-			__mptcp_sockopt_sync(msk, ssk);
-			WRITE_ONCE(subflow->setsockopt_seq, seq);
-		} else if (sseq != seq) {
-			WRITE_ONCE(subflow->setsockopt_seq, seq);
-		}
+	if (READ_ONCE(subflow->setsockopt_seq) != msk->setsockopt_seq) {
+		sync_socket_options(msk, ssk);
 
-		cond_resched();
+		subflow->setsockopt_seq = msk->setsockopt_seq;
 	}
-
-	msk->setsockopt_seq = seq;
 }