[PATCH mptcp-next v4 3/8] mptcp: infinite mapping sending

[Geliang Tang <geliangtang@gmail.com>]

This patch added the infinite mapping sending logic.

Added a new flag send_infinite_map in struct mptcp_subflow_context. Set
it true when a single contiguous subflow is in use 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.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
---
 include/net/mptcp.h  |  3 ++-
 net/mptcp/options.c  |  6 ++++--
 net/mptcp/pm.c       |  6 ++++++
 net/mptcp/protocol.c | 19 +++++++++++++++++++
 net/mptcp/protocol.h | 12 ++++++++++++
 5 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index f83fa48408b3..29e930540ea2 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -35,7 +35,8 @@ struct mptcp_ext {
 			frozen:1,
 			reset_transient:1;
 	u8		reset_reason:4,
-			csum_reqd:1;
+			csum_reqd:1,
+			infinite_map:1;
 };
 
 #define MPTCP_RM_IDS_MAX	8
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 422f4acfb3e6..9c175c298ff6 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -816,8 +816,10 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
 
 	opts->suboptions = 0;
 
-	if (unlikely(__mptcp_check_fallback(msk)))
-		return false;
+	if (unlikely(__mptcp_check_fallback(msk))) {
+		if (!mptcp_check_infinite_map(skb))
+			return false;
+	}
 
 	if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) {
 		if (mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) {
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 6ab386ff3294..4fad1fe8ba10 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -251,7 +251,13 @@ void mptcp_pm_mp_prio_received(struct sock *sk, u8 bkup)
 
 void mptcp_pm_mp_fail_received(struct sock *sk, u64 fail_seq)
 {
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+
 	pr_debug("fail_seq=%llu", fail_seq);
+
+	if (!mptcp_has_another_subflow(sk) && mptcp_is_data_contiguous(msk))
+		subflow->send_infinite_map = 1;
 }
 
 /* path manager helpers */
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index b056672541df..ffef7e1f061b 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1279,6 +1279,23 @@ 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_seq = READ_ONCE(msk->last_fully_acked_dss_start_seq);
+	mpext->subflow_seq = 0;
+	mpext->data_len = 0;
+	mpext->csum = 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)
@@ -1411,6 +1428,8 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 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);
 	mptcp_subflow_ctx(ssk)->rel_write_seq += copy;
 	return copy;
 }
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 2f8a8589668c..cb26183aec9b 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -433,6 +433,7 @@ struct mptcp_subflow_context {
 		backup : 1,
 		send_mp_prio : 1,
 		send_mp_fail : 1,
+		send_infinite_map : 1,
 		rx_eof : 1,
 		can_ack : 1,        /* only after processing the remote a key */
 		disposable : 1,	    /* ctx can be free at ulp release time */
@@ -874,6 +875,17 @@ static inline void mptcp_do_fallback(struct sock *sk)
 
 #define pr_fallback(a) pr_debug("%s:fallback to TCP (msk=%p)", __func__, a)
 
+static inline bool mptcp_check_infinite_map(struct sk_buff *skb)
+{
+	struct mptcp_ext *mpext;
+
+	mpext = skb ? mptcp_get_ext(skb) : NULL;
+	if (mpext && mpext->infinite_map)
+		return true;
+
+	return false;
+}
+
 static inline bool subflow_simultaneous_connect(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
-- 
2.31.1