From 5ced52fa8f0dc23adb067f7b8a009a5ee051efb7 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Oct 2024 17:48:15 +0000 Subject: [PATCH] net: add skb_set_owner_edemux() helper This can be used to attach a socket to an skb, taking a reference on sk->sk_refcnt. This helper might be a NOP if sk->sk_refcnt is zero. Use it from tcp_make_synack(). Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Reviewed-by: Brian Vazquez Link: https://patch.msgid.link/20241010174817.1543642-4-edumazet@google.com Signed-off-by: Jakub Kicinski --- include/net/sock.h | 9 +++++++++ net/core/sock.c | 9 +++------ net/ipv4/tcp_output.c | 2 +- 3 files changed, 13 insertions(+), 7 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index 2f200d91ef115..bf7fa3db10ae7 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1760,6 +1760,15 @@ void sock_efree(struct sk_buff *skb); #ifdef CONFIG_INET void sock_edemux(struct sk_buff *skb); void sock_pfree(struct sk_buff *skb); + +static inline void skb_set_owner_edemux(struct sk_buff *skb, struct sock *sk) +{ + skb_orphan(skb); + if (refcount_inc_not_zero(&sk->sk_refcnt)) { + skb->sk = sk; + skb->destructor = sock_edemux; + } +} #else #define sock_edemux sock_efree #endif diff --git a/net/core/sock.c b/net/core/sock.c index 083d438d8b6fa..f8c0d4eda888c 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2592,14 +2592,11 @@ void __sock_wfree(struct sk_buff *skb) void skb_set_owner_w(struct sk_buff *skb, struct sock *sk) { skb_orphan(skb); - skb->sk = sk; #ifdef CONFIG_INET - if (unlikely(!sk_fullsock(sk))) { - skb->destructor = sock_edemux; - sock_hold(sk); - return; - } + if (unlikely(!sk_fullsock(sk))) + return skb_set_owner_edemux(skb, sk); #endif + skb->sk = sk; skb->destructor = sock_wfree; skb_set_hash_from_sk(skb, sk); /* diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 06200bb111f8b..054244ce51175 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3728,7 +3728,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, switch (synack_type) { case TCP_SYNACK_NORMAL: - skb_set_owner_w(skb, req_to_sk(req)); + skb_set_owner_edemux(skb, req_to_sk(req)); break; case TCP_SYNACK_COOKIE: /* Under synflood, we do not attach skb to a socket,