netdev - Re: [PATCH bpf-next v3 2/3] libbpf: add low level TC-BPF API

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Date:   Wed, 21 Apr 2021 18:56:20 -0700
From:   Yonghong Song <yhs@...com>
To:     Kumar Kartikeya Dwivedi <memxor@...il.com>
CC:     <bpf@...r.kernel.org>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf-next v3 2/3] libbpf: add low level TC-BPF API



On 4/21/21 10:06 AM, Kumar Kartikeya Dwivedi wrote:
> On Wed, Apr 21, 2021 at 12:28:01PM IST, Yonghong Song wrote:
>>
>>
>> On 4/20/21 12:37 PM, Kumar Kartikeya Dwivedi wrote:
>>> This adds functions that wrap the netlink API used for adding,
>>> manipulating, and removing traffic control filters. These functions
>>> operate directly on the loaded prog's fd, and return a handle to the
>>> filter using an out parameter named id.
>>>
>>> The basic featureset is covered to allow for attaching and removal of
>>> filters. Some additional features like TCA_BPF_POLICE and TCA_RATE for
>>> the API have been omitted. These can added on top later by extending the
>>
>> "later" => "layer"?
>>
> 
> No, I meant that other options can be added on top of this series by someone
> later. I'll reword it.
> 
[...]
>>>
>>> Reviewed-by: Toke Høiland-Jørgensen <toke@...hat.com>
>>> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@...il.com>
>>> ---
>>>    tools/lib/bpf/libbpf.h   |  44 ++++++
>>>    tools/lib/bpf/libbpf.map |   3 +
>>>    tools/lib/bpf/netlink.c  | 319 ++++++++++++++++++++++++++++++++++++++-
>>>    3 files changed, 360 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
>>> index bec4e6a6e31d..b4ed6a41ea70 100644
>>> --- a/tools/lib/bpf/libbpf.h
>>> +++ b/tools/lib/bpf/libbpf.h
>>> @@ -16,6 +16,8 @@
>>>    #include <stdbool.h>
>>>    #include <sys/types.h>  // for size_t
>>>    #include <linux/bpf.h>
>>> +#include <linux/pkt_sched.h>
>>> +#include <linux/tc_act/tc_bpf.h>
>>>    #include "libbpf_common.h"
>>> @@ -775,6 +777,48 @@ LIBBPF_API int bpf_linker__add_file(struct bpf_linker *linker, const char *filen
>>>    LIBBPF_API int bpf_linker__finalize(struct bpf_linker *linker);
>>>    LIBBPF_API void bpf_linker__free(struct bpf_linker *linker);
>>> +/* Convenience macros for the clsact attach hooks */
>>> +#define BPF_TC_CLSACT_INGRESS TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_INGRESS)
>>> +#define BPF_TC_CLSACT_EGRESS TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_EGRESS)
>>> +
>>> +struct bpf_tc_opts {
>>> +	size_t sz;
>>> +	__u32 handle;
>>> +	__u32 class_id;
>>> +	__u16 priority;
>>> +	bool replace;
>>> +	size_t :0;
>>
>> Did you see any error without "size_t :0"?
>>
> 
> Not really, I just added this considering this recent change:
> dde7b3f5f2f4 ("libbpf: Add explicit padding to bpf_xdp_set_link_opts")

Thanks. That is fine with me then.

> 
>>> +};
>>> +
>>> +#define bpf_tc_opts__last_field replace
>>> +
>>> +/* Acts as a handle for an attached filter */
>>> +struct bpf_tc_attach_id {
>>> +	__u32 handle;
>>> +	__u16 priority;
>>> +};
>>> +
>> [...]
> 
> --
> Kartikeya
>