mptcp: infinite mapping sending

This patch adds the infinite mapping sending logic.

Add a new flag send_infinite_map in struct mptcp_subflow_context. Set
it true when a single contiguous subflow is in use and the
allow_infinite_fallback flag is true in mptcp_pm_mp_fail_received().

In mptcp_sendmsg_frag(), if this flag is true, call the new function
mptcp_update_infinite_map() to set the infinite mapping.

Add a new flag infinite_map in struct mptcp_ext, set it true in
mptcp_update_infinite_map(), and check this flag in a new helper
mptcp_check_infinite_map().

In mptcp_update_infinite_map(), set data_len to 0, and clear the
send_infinite_map flag, then do fallback.

In mptcp_established_options(), use the helper mptcp_check_infinite_map()
to let the infinite mapping DSS can be sent out in the fallback mode.

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

1 files changed, 17 insertions, 0 deletions

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 6d653914e9fe..161c07f49db6 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1229,6 +1229,21 @@ static void mptcp_update_data_checksum(struct sk_buff *skb, int added)
 	mpext->csum = csum_fold(csum_block_add(csum, skb_checksum(skb, offset, added, 0), offset));
 }
 
+static void mptcp_update_infinite_map(struct mptcp_sock *msk,
+				      struct sock *ssk,
+				      struct mptcp_ext *mpext)
+{
+	if (!mpext)
+		return;
+
+	mpext->infinite_map = 1;
+	mpext->data_len = 0;
+
+	mptcp_subflow_ctx(ssk)->send_infinite_map = 0;
+	pr_fallback(msk);
+	__mptcp_do_fallback(msk);
+}
+
 static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 			      struct mptcp_data_frag *dfrag,
 			      struct mptcp_sendmsg_info *info)
@@ -1360,6 +1375,8 @@ alloc_skb:
 out:
 	if (READ_ONCE(msk->csum_enabled))
 		mptcp_update_data_checksum(skb, copy);
+	if (mptcp_subflow_ctx(ssk)->send_infinite_map)
+		mptcp_update_infinite_map(msk, ssk, mpext);
 	trace_mptcp_sendmsg_frag(mpext);
 	mptcp_subflow_ctx(ssk)->rel_write_seq += copy;
 	return copy;