From 68c7af988bd137479101e2b40ab5fdd0e0365364 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Sat, 27 Sep 2025 11:40:42 +0200 Subject: [PATCH] mptcp: factor out a basic skb coalesce helper The upcoming patch will introduced backlog processing for MPTCP socket, and we want to leverage coalescing in such data path. Factor out the relevant bits not touching memory accounting to deal with such use-case. Co-developed-by: Geliang Tang Signed-off-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Paolo Abeni Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250927-net-next-mptcp-rcv-path-imp-v1-6-5da266aa9c1a@kernel.org Signed-off-by: Jakub Kicinski --- net/mptcp/protocol.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 26fbd9f6a3f78..da21f1807729a 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -142,22 +142,33 @@ static void mptcp_drop(struct sock *sk, struct sk_buff *skb) __kfree_skb(skb); } -static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to, - struct sk_buff *from) +static bool __mptcp_try_coalesce(struct sock *sk, struct sk_buff *to, + struct sk_buff *from, bool *fragstolen, + int *delta) { - bool fragstolen; - int delta; + int limit = READ_ONCE(sk->sk_rcvbuf); if (unlikely(MPTCP_SKB_CB(to)->cant_coalesce) || MPTCP_SKB_CB(from)->offset || - ((to->len + from->len) > (sk->sk_rcvbuf >> 3)) || - !skb_try_coalesce(to, from, &fragstolen, &delta)) + ((to->len + from->len) > (limit >> 3)) || + !skb_try_coalesce(to, from, fragstolen, delta)) return false; pr_debug("colesced seq %llx into %llx new len %d new end seq %llx\n", MPTCP_SKB_CB(from)->map_seq, MPTCP_SKB_CB(to)->map_seq, to->len, MPTCP_SKB_CB(from)->end_seq); MPTCP_SKB_CB(to)->end_seq = MPTCP_SKB_CB(from)->end_seq; + return true; +} + +static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to, + struct sk_buff *from) +{ + bool fragstolen; + int delta; + + if (!__mptcp_try_coalesce(sk, to, from, &fragstolen, &delta)) + return false; /* note the fwd memory can reach a negative value after accounting * for the delta, but the later skb free will restore a non -- 2.47.3