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skmsg: Move sk_redir from TCP_SKB_CB to skb

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Currently TCP_SKB_CB() is hard-coded in skmsg code, it certainly
does not work for any other non-TCP protocols. We can move them to
skb ext, but it introduces a memory allocation on fast path.

Fortunately, we only need to a word-size to store all the information,
because the flags actually only contains 1 bit so can be just packed
into the lowest bit of the "pointer", which is stored as unsigned
long.

Inside struct sk_buff, '_skb_refdst' can be reused because skb dst is
no longer needed after ->sk_data_ready() so we can just drop it.

Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210223184934.6054-5-xiyou.wangcong@gmail.com
This commit is contained in:
Cong Wang
2021-02-23 10:49:29 -08:00
committed by Alexei Starovoitov
parent 16137b09a6
commit e3526bb92a
5 changed files with 62 additions and 37 deletions
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38
include/linux/skmsg.h
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@@ -455,4 +455,42 @@ static inline bool sk_psock_strp_enabled(struct sk_psock *psock)
return false;
return !!psock->saved_data_ready;
}
#if IS_ENABLED(CONFIG_NET_SOCK_MSG)
/* We only have one bit so far. */
#define BPF_F_PTR_MASK ~(BPF_F_INGRESS)
static inline bool skb_bpf_ingress(const struct sk_buff *skb)
{
unsigned long sk_redir = skb->_sk_redir;
return sk_redir & BPF_F_INGRESS;
}
static inline void skb_bpf_set_ingress(struct sk_buff *skb)
{
skb->_sk_redir |= BPF_F_INGRESS;
}
static inline void skb_bpf_set_redir(struct sk_buff *skb, struct sock *sk_redir,
bool ingress)
{
skb->_sk_redir = (unsigned long)sk_redir;
if (ingress)
skb->_sk_redir |= BPF_F_INGRESS;
}
static inline struct sock *skb_bpf_redirect_fetch(const struct sk_buff *skb)
{
unsigned long sk_redir = skb->_sk_redir;
return (struct sock *)(sk_redir & BPF_F_PTR_MASK);
}
static inline void skb_bpf_redirect_clear(struct sk_buff *skb)
{
skb->_sk_redir = 0;
}
#endif /* CONFIG_NET_SOCK_MSG */
#endif /* _LINUX_SKMSG_H */