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SubjectRe: [PATCH net-next 1/3] net: ip: add skb drop reasons for ip egress path
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On 2/20/22 8:57 AM, menglong8.dong@gmail.com wrote:
> From: Menglong Dong <imagedong@tencent.com>
>
> Replace kfree_skb() with kfree_skb_reason() in the packet egress path of
> IP layer (both IPv4 and IPv6 are considered).
>
> Following functions are involved:
>
> __ip_queue_xmit()
> ip_finish_output()
> ip_mc_finish_output()
> ip6_output()
> ip6_finish_output()
> ip6_finish_output2()
>
> Following new drop reasons are introduced:
>
> SKB_DROP_REASON_IP_OUTNOROUTES
> SKB_DROP_REASON_BPF_CGROUP_EGRESS
> SKB_DROP_REASON_IPV6DSIABLED
>
> Reviewed-by: Mengen Sun <mengensun@tencent.com>
> Reviewed-by: Hao Peng <flyingpeng@tencent.com>
> Signed-off-by: Menglong Dong <imagedong@tencent.com>
> ---
> include/linux/skbuff.h | 13 +++++++++++++
> include/trace/events/skb.h | 4 ++++
> net/ipv4/ip_output.c | 6 +++---
> net/ipv6/ip6_output.c | 6 +++---
> 4 files changed, 23 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index a3e90efe6586..c310a4a8fc86 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -380,6 +380,19 @@ enum skb_drop_reason {
> * the ofo queue, corresponding to
> * LINUX_MIB_TCPOFOMERGE
> */
> + SKB_DROP_REASON_IP_OUTNOROUTES, /* route lookup failed during
> + * packet outputting
> + */

This should be good enough since the name contains OUT.

/* route lookup failed */

> + SKB_DROP_REASON_BPF_CGROUP_EGRESS, /* dropped by eBPF program
> + * with type of BPF_PROG_TYPE_CGROUP_SKB
> + * and attach type of
> + * BPF_CGROUP_INET_EGRESS
> + * during packet sending
> + */

/* dropped by BPF_CGROUP_INET_EGRESS eBPF program */

> + SKB_DROP_REASON_IPV6DSIABLED, /* IPv6 is disabled on the device,
> + * see the doc for disable_ipv6
> + * in ip-sysctl.rst for detail
> + */

Just /* IPv6 is disabled on the device */


> SKB_DROP_REASON_MAX,
> };
>

> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
> index 0c0574eb5f5b..df549b7415fb 100644
> --- a/net/ipv4/ip_output.c
> +++ b/net/ipv4/ip_output.c

This file has other relevant drops. e.g., ip_finish_output2 when a neigh
entry can not be created and after skb_gso_segment. The other set for
tun/tap devices has SKB_DROP_REASON_SKB_GSO_SEG which can be used for
the latter. That set also adds kfree_skb_list_reason for the frag drops.


> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index 0c6c971ce0a5..4cd9e5fd25e4 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c

Similarly here. The other set should land in the next few days, so you
cna put this set on top of it.

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