From: Daniel Borkmann <daniel@iogearbox.net>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: bpf@vger.kernel.org, "Toke Høiland-Jørgensen" <toke@redhat.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Martin KaFai Lau" <kafai@fb.com>,
"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
"John Fastabend" <john.fastabend@gmail.com>,
"KP Singh" <kpsingh@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
"Jakub Kicinski" <kuba@kernel.org>,
"Jesper Dangaard Brouer" <brouer@redhat.com>,
netdev@vger.kernel.org
Subject: Re: [PATCH bpf-next v3 2/3] libbpf: add low level TC-BPF API
Date: Thu, 22 Apr 2021 01:21:55 +0200 [thread overview]
Message-ID: <21c55619-e26d-d901-076e-20f55302c2fd@iogearbox.net> (raw)
In-Reply-To: <20210421230858.ruwqw5jvsy7cjioy@apollo>
On 4/22/21 1:08 AM, Kumar Kartikeya Dwivedi wrote:
> On Thu, Apr 22, 2021 at 04:29:28AM IST, Daniel Borkmann wrote:
>> On 4/20/21 9:37 PM, Kumar Kartikeya Dwivedi wrote:
>> [...]
>>> 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)
>>
>> I would abstract those away into an enum, plus avoid having to pull in
>> linux/pkt_sched.h and linux/tc_act/tc_bpf.h from main libbpf.h header.
>>
>> Just add a enum { BPF_TC_DIR_INGRESS, BPF_TC_DIR_EGRESS, } and then the
>> concrete tc bits (TC_H_MAKE()) can be translated internally.
>
> Ok, will do.
>
>>> +struct bpf_tc_opts {
>>> + size_t sz;
>>
>> Is this set anywhere?
>
> This is needed by the OPTS_* infrastructure.
>
>>> + __u32 handle;
>>> + __u32 class_id;
>>
>> I'd remove class_id from here as well given in direct-action a BPF prog can
>> set it if needed.
>
> Ok, makes sense.
>
>>> + __u16 priority;
>>> + bool replace;
>>> + size_t :0;
>>
>> What's the rationale for this padding?
>
> dde7b3f5f2f4 ("libbpf: Add explicit padding to bpf_xdp_set_link_opts")
Hm, fair enough.
>>> +};
>>> +
>>> +#define bpf_tc_opts__last_field replace
>>> +
>>> +/* Acts as a handle for an attached filter */
>>> +struct bpf_tc_attach_id {
>>
>> nit: maybe bpf_tc_ctx
>>
>
> Noted.
>
>>> + __u32 handle;
>>> + __u16 priority;
>>> +};
>>> +
>>> +struct bpf_tc_info {
>>> + struct bpf_tc_attach_id id;
>>> + __u16 protocol;
>>> + __u32 chain_index;
>>> + __u32 prog_id;
>>> + __u8 tag[BPF_TAG_SIZE];
>>> + __u32 class_id;
>>> + __u32 bpf_flags;
>>> + __u32 bpf_flags_gen;
>>
>> Given we do not yet have any setters e.g. for offload, etc, the one thing
>> I'd see useful and crucial initially is prog_id.
>>
>> The protocol, chain_index, and I would also include tag should be dropped.
>
> A future user of this API needs to know the tag, so I would like to keep that.
> The rest we can drop, and probably document the default values explicitly.
Couldn't this be added along with the future patch for the [future] user?
The tag should be the tag of the prog itself, so if you have prog_id, you
could also retrieve the same tag from the prog. The tag was basically from
the early days where we didn't have bpf_prog_get_info_by_fd().
What does that future user need to do different here?
Thanks,
Daniel
next prev parent reply other threads:[~2021-04-21 23:22 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-20 19:37 [PATCH bpf-next v3 0/3] Add TC-BPF API Kumar Kartikeya Dwivedi
2021-04-20 19:37 ` [PATCH bpf-next v3 1/3] libbpf: add helpers for preparing netlink attributes Kumar Kartikeya Dwivedi
2021-04-21 6:37 ` Yonghong Song
2021-04-20 19:37 ` [PATCH bpf-next v3 2/3] libbpf: add low level TC-BPF API Kumar Kartikeya Dwivedi
2021-04-21 6:58 ` Yonghong Song
2021-04-21 17:06 ` Kumar Kartikeya Dwivedi
2021-04-22 1:56 ` Yonghong Song
2021-04-21 18:19 ` Andrii Nakryiko
2021-04-21 19:48 ` Toke Høiland-Jørgensen
2021-04-21 23:14 ` Daniel Borkmann
2021-04-22 9:08 ` Toke Høiland-Jørgensen
2021-04-22 11:51 ` Daniel Borkmann
2021-04-22 12:46 ` Toke Høiland-Jørgensen
2021-04-21 22:59 ` Daniel Borkmann
2021-04-21 23:08 ` Kumar Kartikeya Dwivedi
2021-04-21 23:21 ` Daniel Borkmann [this message]
2021-04-21 23:30 ` Kumar Kartikeya Dwivedi
2021-04-21 23:41 ` Daniel Borkmann
2021-04-22 9:47 ` Shaun Crampton
2021-04-22 11:26 ` Daniel Borkmann
2021-04-22 3:43 ` Andrii Nakryiko
2021-04-22 15:35 ` Daniel Borkmann
2021-04-22 18:28 ` Andrii Nakryiko
2021-04-20 19:37 ` [PATCH bpf-next v3 3/3] libbpf: add selftests for " Kumar Kartikeya Dwivedi
2021-04-21 7:01 ` Yonghong Song
2021-04-21 18:24 ` Andrii Nakryiko
2021-04-21 19:56 ` Kumar Kartikeya Dwivedi
2021-04-21 20:38 ` Toke Høiland-Jørgensen
2021-04-21 22:41 ` Daniel Borkmann
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