netdev - Re: [PATCH bpf-next v1 11/13] libbpf: Support creating and destroying qdisc

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Message-ID: <CAEf4BzY5E7JEPJ_W3T-bcKmdAJa-zpM4G+4H2rv2dOtLZMFbvA@mail.gmail.com>
Date: Tue, 17 Dec 2024 10:32:23 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Amery Hung <amery.hung@...edance.com>
Cc: netdev@...r.kernel.org, bpf@...r.kernel.org, daniel@...earbox.net, 
	andrii@...nel.org, alexei.starovoitov@...il.com, martin.lau@...nel.org, 
	sinquersw@...il.com, toke@...hat.com, jhs@...atatu.com, jiri@...nulli.us, 
	stfomichev@...il.com, ekarani.silvestre@....ufcg.edu.br, 
	yangpeihao@...u.edu.cn, xiyou.wangcong@...il.com, yepeilin.cs@...il.com, 
	ameryhung@...il.com
Subject: Re: [PATCH bpf-next v1 11/13] libbpf: Support creating and destroying qdisc

On Fri, Dec 13, 2024 at 3:30 PM Amery Hung <amery.hung@...edance.com> wrote:
>
> Extend struct bpf_tc_hook with handle, qdisc name and a new attach type,
> BPF_TC_QDISC, to allow users to add or remove any qdisc specified in
> addition to clsact.
>
> Signed-off-by: Amery Hung <amery.hung@...edance.com>
> ---
>  tools/lib/bpf/libbpf.h  |  5 ++++-
>  tools/lib/bpf/netlink.c | 20 +++++++++++++++++---
>  2 files changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index b2ce3a72b11d..b05d95814776 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -1268,6 +1268,7 @@ enum bpf_tc_attach_point {
>         BPF_TC_INGRESS = 1 << 0,
>         BPF_TC_EGRESS  = 1 << 1,
>         BPF_TC_CUSTOM  = 1 << 2,
> +       BPF_TC_QDISC   = 1 << 3,
>  };
>
>  #define BPF_TC_PARENT(a, b)    \
> @@ -1282,9 +1283,11 @@ struct bpf_tc_hook {
>         int ifindex;
>         enum bpf_tc_attach_point attach_point;
>         __u32 parent;
> +       __u32 handle;
> +       char *qdisc;

const char *?

>         size_t :0;
>  };
> -#define bpf_tc_hook__last_field parent
> +#define bpf_tc_hook__last_field qdisc
>
>  struct bpf_tc_opts {
>         size_t sz;
> diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c
> index 68a2def17175..72db8c0add21 100644
> --- a/tools/lib/bpf/netlink.c
> +++ b/tools/lib/bpf/netlink.c
> @@ -529,9 +529,9 @@ int bpf_xdp_query_id(int ifindex, int flags, __u32 *prog_id)
>  }
>
>
> -typedef int (*qdisc_config_t)(struct libbpf_nla_req *req);
> +typedef int (*qdisc_config_t)(struct libbpf_nla_req *req, struct bpf_tc_hook *hook);

should hook pointer be const?

>
> -static int clsact_config(struct libbpf_nla_req *req)
> +static int clsact_config(struct libbpf_nla_req *req, struct bpf_tc_hook *hook)

const?

>  {
>         req->tc.tcm_parent = TC_H_CLSACT;
>         req->tc.tcm_handle = TC_H_MAKE(TC_H_CLSACT, 0);
> @@ -539,6 +539,16 @@ static int clsact_config(struct libbpf_nla_req *req)
>         return nlattr_add(req, TCA_KIND, "clsact", sizeof("clsact"));
>  }
>
> +static int qdisc_config(struct libbpf_nla_req *req, struct bpf_tc_hook *hook)

same, const, it's not written into, right?

> +{
> +       char *qdisc = OPTS_GET(hook, qdisc, NULL);
> +
> +       req->tc.tcm_parent = OPTS_GET(hook, parent, TC_H_ROOT);
> +       req->tc.tcm_handle = OPTS_GET(hook, handle, 0);
> +
> +       return nlattr_add(req, TCA_KIND, qdisc, strlen(qdisc) + 1);
> +}
> +
>  static int attach_point_to_config(struct bpf_tc_hook *hook,
>                                   qdisc_config_t *config)
>  {
> @@ -552,6 +562,9 @@ static int attach_point_to_config(struct bpf_tc_hook *hook,
>                 return 0;
>         case BPF_TC_CUSTOM:
>                 return -EOPNOTSUPP;
> +       case BPF_TC_QDISC:
> +               *config = &qdisc_config;
> +               return 0;
>         default:
>                 return -EINVAL;
>         }
> @@ -596,7 +609,7 @@ static int tc_qdisc_modify(struct bpf_tc_hook *hook, int cmd, int flags)
>         req.tc.tcm_family  = AF_UNSPEC;
>         req.tc.tcm_ifindex = OPTS_GET(hook, ifindex, 0);
>
> -       ret = config(&req);
> +       ret = config(&req, hook);
>         if (ret < 0)
>                 return ret;
>
> @@ -639,6 +652,7 @@ int bpf_tc_hook_destroy(struct bpf_tc_hook *hook)
>         case BPF_TC_INGRESS:
>         case BPF_TC_EGRESS:
>                 return libbpf_err(__bpf_tc_detach(hook, NULL, true));
> +       case BPF_TC_QDISC:
>         case BPF_TC_INGRESS | BPF_TC_EGRESS:
>                 return libbpf_err(tc_qdisc_delete(hook));
>         case BPF_TC_CUSTOM:
> --
> 2.20.1
>