lkml.org 
[lkml]   [2015]   [Jul]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Draft 3 of bpf(2) man page for review
On 07/23/2015 12:12 AM, Alexei Starovoitov wrote:
> On 7/22/15 1:10 PM, Michael Kerrisk (man-pages) wrote:
>> BPF maps are a generic data structure for storage of different
>> data types. A user process can create multiple maps (with
>> key/value-pairs being opaque bytes of data) and access them via
>> file descriptors. Differnt eBPF programs can access the same
>> maps in parallel. It's up to the user process and eBPF program
>> to decide what they store inside maps.
>
> typo in 'Different'

Fixed.

>> eBPF program types
>> By picking prog_type, the program author selects a set of helper
>> functions that can be called from the eBPF program and the corre‐
>> sponding format of struct bpf_context (which is the data blob
>> passed into the eBPF program as the first argument). For exam‐
>> ple, programs loaded with a prog_type of
>> BPF_PROG_TYPE_SOCKET_FILTER may call the bpf_map_lookup_elem()
>> helper, whereas some other program types may not be able to
>> employ this helper. The set of functions available to eBPF pro‐
>> grams of a given type may increase in the future.
>
> overall it's all correct, but today bpf_map_lookup_elem() is allowed
> for all program types. May be change that to:
> "BPF_PROG_TYPE_KPROBE may call the bpf_probe_read() helper"
> since only type_kprobe programs can call it.
> type_sockets/type_sched_* cannot.

Changed, as you suggest.

>> The bpf_context argument is a pointer to a struct sk_buff.
>> Programs cannot access the fields of sk_buff directly.
>
> Probably drop last sentence and replace 'sk_buff' with '__sk_buff'
> in the first? Or for the first version we can drop both sentences.

I did the former.

> The rest looks great. Thank you much!

Thanks,

Michael



--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/


\
 
 \ /
  Last update: 2015-07-23 12:21    [W:0.130 / U:0.136 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site