mptcp: introduce the mptcp_init_skb helper

Factor out all the skb initialization step in a new helper and
use it. Note that this change moves the MPTCP CB initialization
earlier: we can do such step as soon as the skb leaves the
subflow socket receive queues.

Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Geliang Tang <geliang@kernel.org>
Tested-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250927-net-next-mptcp-rcv-path-imp-v1-4-5da266aa9c1a@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index f994e7f45f7b96c280708d7a29c1423a91e4cfee..832782e23740d22acda608966c29516666c9b111 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -326,27 +326,11 @@ end:
                mptcp_rcvbuf_grow(sk);
 }
 
-static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
-                            struct sk_buff *skb, unsigned int offset,
-                            size_t copy_len)
+static void mptcp_init_skb(struct sock *ssk, struct sk_buff *skb, int offset,
+                          int copy_len)
 {
-       struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
-       struct sock *sk = (struct sock *)msk;
-       struct sk_buff *tail;
-       bool has_rxtstamp;
-
-       __skb_unlink(skb, &ssk->sk_receive_queue);
-
-       skb_ext_reset(skb);
-       skb_orphan(skb);
-
-       /* try to fetch required memory from subflow */
-       if (!sk_rmem_schedule(sk, skb, skb->truesize)) {
-               MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RCVPRUNED);
-               goto drop;
-       }
-
-       has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;
+       const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+       bool has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;
 
        /* the skb map_seq accounts for the skb offset:
         * mptcp_subflow_get_mapped_dsn() is based on the current tp->copied_seq
@@ -358,6 +342,24 @@ static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
        MPTCP_SKB_CB(skb)->has_rxtstamp = has_rxtstamp;
        MPTCP_SKB_CB(skb)->cant_coalesce = 0;
 
+       __skb_unlink(skb, &ssk->sk_receive_queue);
+
+       skb_ext_reset(skb);
+       skb_dst_drop(skb);
+}
+
+static bool __mptcp_move_skb(struct sock *sk, struct sk_buff *skb)
+{
+       u64 copy_len = MPTCP_SKB_CB(skb)->end_seq - MPTCP_SKB_CB(skb)->map_seq;
+       struct mptcp_sock *msk = mptcp_sk(sk);
+       struct sk_buff *tail;
+
+       /* try to fetch required memory from subflow */
+       if (!sk_rmem_schedule(sk, skb, skb->truesize)) {
+               MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RCVPRUNED);
+               goto drop;
+       }
+
        if (MPTCP_SKB_CB(skb)->map_seq == msk->ack_seq) {
                /* in sequence */
                msk->bytes_received += copy_len;
@@ -678,7 +680,9 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
                if (offset < skb->len) {
                        size_t len = skb->len - offset;
 
-                       ret = __mptcp_move_skb(msk, ssk, skb, offset, len) || ret;
+                       mptcp_init_skb(ssk, skb, offset, len);
+                       skb_orphan(skb);
+                       ret = __mptcp_move_skb(sk, skb) || ret;
                        seq += len;
 
                        if (unlikely(map_remaining < len)) {