On Wed, Mar 2, 2022 at 11:56 AM Martin KaFai Lau <kafai@xxxxxx> wrote:
>
> The previous patches handled the delivery_time in the ingress path
> before the routing decision is made. This patch can postpone clearing
> delivery_time in a skb until knowing it is delivered locally and also
> set the (rcv) timestamp if needed. This patch moves the
> skb_clear_delivery_time() from dev.c to ip_local_deliver_finish()
> and ip6_input_finish().
>
> Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
> ---
> net/core/dev.c | 8 ++------
> net/ipv4/ip_input.c | 1 +
> net/ipv6/ip6_input.c | 1 +
> 3 files changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 0fc02cf32476..3ff686cc8c84 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -5193,10 +5193,8 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
> goto out;
> }
>
> - if (skb_skip_tc_classify(skb)) {
> - skb_clear_delivery_time(skb);
> + if (skb_skip_tc_classify(skb))
> goto skip_classify;
> - }
>
> if (pfmemalloc)
> goto skip_taps;
> @@ -5225,14 +5223,12 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
> goto another_round;
> if (!skb)
> goto out;
> - skb_clear_delivery_time(skb);
>
> nf_skip_egress(skb, false);
> if (nf_ingress(skb, &pt_prev, &ret, orig_dev) < 0)
> goto out;
> - } else
> + }
> #endif
> - skb_clear_delivery_time(skb);
> skb_reset_redirect(skb);
> skip_classify:
> if (pfmemalloc && !skb_pfmemalloc_protocol(skb))
> diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
> index d94f9f7e60c3..95f7bb052784 100644
> --- a/net/ipv4/ip_input.c
> +++ b/net/ipv4/ip_input.c
> @@ -226,6 +226,7 @@ void ip_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int protocol)
>
> static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
> {
> + skb_clear_delivery_time(skb);
> __skb_pull(skb, skb_network_header_len(skb));
>
> rcu_read_lock();
> diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
> index d4b1e2c5aa76..5b5ea35635f9 100644
> --- a/net/ipv6/ip6_input.c
> +++ b/net/ipv6/ip6_input.c
> @@ -459,6 +459,7 @@ void ip6_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int nexthdr,
>
> static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
> {
> + skb_clear_delivery_time(skb);
> rcu_read_lock();
> ip6_protocol_deliver_rcu(net, skb, 0, false);
> rcu_read_unlock();
> --
> 2.30.2
>
It is not clear to me why we need to clear tstamp if packet is locally
delivered ?
TCP stack is using tstamp for incoming packets (look for
TCP_SKB_CB(skb)->has_rxtstamp)
