netdev - Re: [PATCH bpf-next v3 8/8] bpf: add documentation for eBPF helpers (58-64)

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Message-ID: <67e84a95-5e7b-1c2c-e90f-7bcc0026bd10@netronome.com>
Date:   Wed, 18 Apr 2018 15:09:41 +0100
From:   Quentin Monnet <quentin.monnet@...ronome.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     daniel@...earbox.net, ast@...nel.org, netdev@...r.kernel.org,
        oss-drivers@...ronome.com, linux-doc@...r.kernel.org,
        linux-man@...r.kernel.org,
        John Fastabend <john.fastabend@...il.com>
Subject: Re: [PATCH bpf-next v3 8/8] bpf: add documentation for eBPF helpers
 (58-64)

2018-04-18 15:34 UTC+0200 ~ Jesper Dangaard Brouer <brouer@...hat.com>
> On Tue, 17 Apr 2018 15:34:38 +0100
> Quentin Monnet <quentin.monnet@...ronome.com> wrote:
> 
>> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
>> index 350459c583de..3d329538498f 100644
>> --- a/include/uapi/linux/bpf.h
>> +++ b/include/uapi/linux/bpf.h
>> @@ -1276,6 +1276,50 @@ union bpf_attr {
>>   * 	Return
>>   * 		0 on success, or a negative error in case of failure.
>>   *
>> + * int bpf_redirect_map(struct bpf_map *map, u32 key, u64 flags)
>> + * 	Description
>> + * 		Redirect the packet to the endpoint referenced by *map* at
>> + * 		index *key*. Depending on its type, his *map* can contain
>                                                     ^^^
> 
> "his" -> "this"

Thanks!

>> + * 		references to net devices (for forwarding packets through other
>> + * 		ports), or to CPUs (for redirecting XDP frames to another CPU;
>> + * 		but this is only implemented for native XDP (with driver
>> + * 		support) as of this writing).
>> + *
>> + * 		All values for *flags* are reserved for future usage, and must
>> + * 		be left at zero.
>> + * 	Return
>> + * 		**XDP_REDIRECT** on success, or **XDP_ABORT** on error.
>> + *
> 
> "XDP_ABORT" -> "XDP_ABORTED"

Ouch. And I did the same for bpf_redirect(). Thanks for the catch.

> 
> I don't know if it's worth mentioning in the doc/man-page; that for XDP
> using bpf_redirect_map() is a HUGE performance advantage, compared to
> the bpf_redirect() call ?

It seems worth to me. How would you simply explain the reason for this
difference?

Quentin