netdev - Re: [PATCH v3 bpf-next 4/4] bpftool: support loading flow dissector

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Date:   Thu, 8 Nov 2018 13:54:26 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Stanislav Fomichev <sdf@...ichev.me>
Cc:     Stanislav Fomichev <sdf@...gle.com>, netdev@...r.kernel.org,
        linux-kselftest@...r.kernel.org, ast@...nel.org,
        daniel@...earbox.net, shuah@...nel.org,
        quentin.monnet@...ronome.com, guro@...com,
        jiong.wang@...ronome.com, bhole_prashant_q7@....ntt.co.jp,
        john.fastabend@...il.com, jbenc@...hat.com,
        treeze.taeung@...il.com, yhs@...com, osk@...com,
        sandipan@...ux.vnet.ibm.com
Subject: Re: [PATCH v3 bpf-next 4/4] bpftool: support loading flow dissector

On Thu, 8 Nov 2018 13:29:40 -0800, Stanislav Fomichev wrote:
> On 11/08, Jakub Kicinski wrote:
> > On Wed,  7 Nov 2018 21:39:57 -0800, Stanislav Fomichev wrote:  
> > > This commit adds support for loading/attaching/detaching flow
> > > dissector program. The structure of the flow dissector program is
> > > assumed to be the same as in the selftests:
> > > 
> > > * flow_dissector section with the main entry point
> > > * a bunch of tail call progs
> > > * a jmp_table map that is populated with the tail call progs  
> > 
> > Could you split the loadall changes and the flow_dissector changes into
> > two separate patches?  
> Sure, will do, but let's first agree on the semantical differences of
> load vs loadall.
> 
> So far *load* actually loads _all_ progs (via bpf_object__load), but pins
> only the first program. Is that what we want? I wonder whether the
> assumption there was that there is only single program in the object.
> Should we load only the first program in *load*?
> 
> If we add *loadall*, then the difference would be:
> *load*:
>   * loads all maps and only the first program, pins only the first
>     program
> *loadall*:
>   * loads all maps and all programs, pins everything (maps and programs)
> 
> Is this the expected behavior?

Loading all programs and maps for "load" is just a libbpf limitation we
can remove at some point.