On Thu, 8 Nov 2018 13:20:12 -0800, Stanislav Fomichev wrote:
> On 11/08, Jakub Kicinski wrote:
> > On Thu, 8 Nov 2018 18:21:24 +0000, Quentin Monnet wrote:
> > > >>> @@ -79,8 +82,11 @@ DESCRIPTION
> > > >>> contain a dot character ('.'), which is reserved for
> > > >>> future
> > > >>> extensions of *bpffs*.
> > > >>> - **bpftool prog load** *OBJ* *FILE* [**type** *TYPE*] [**map**
> > > >>> {**idx** *IDX* | **name** *NAME*} *MAP*] [**dev** *NAME*]
> > > >>> + **bpftool prog { load | loadall }** *OBJ* *FILE* [**type**
> > > >>> *TYPE*] [**map** {**idx** *IDX* | **name** *NAME*} *MAP*] [**dev**
> > > >>> *NAME*]
> > > >>> Load bpf program from binary *OBJ* and pin as *FILE*.
> > > >>> + **bpftool prog load** will pin only the first bpf
> > > >>> program
> > > >>> + from the *OBJ*, **bpftool prog loadall** will pin all
> > > >>> maps
> > > >>> + and programs from the *OBJ*.
> > > >>
> > > >> This could be improved regarding maps: with "bpftool prog load" I
> > > >> think we
> > > >> also load and pin all maps, but your description implies this is only
> > > >> the
> > > >> case with "loadall"
> > > > I don't think we pin any maps with `bpftool prog load`, we certainly
> > > > load
> > > > them, but we don't pin any afaict. Can you point me to the code where we
> > > > pin the maps?
> > > >
> > >
> > > My bad. I read "pin" but thought "load". It does not pin them indeed,
> > > sorry about that.
> >
> > Right, but I don't see much reason why prog loadall should pin maps.
> It does seem convenient to have an option to pin everything, so we
> don't require anything else to find the ids of the maps.
> If we are pinning all progs, might as well pin the maps, why not? See
> my example in the commit message, for example, where I just hard code
> the expected map name. Convenient :-)
Sure. I can see how its convenient to your use case. A lot of people
will be very used to finding out the maps because if program is loaded
with iproute2 tools neither programs nor maps get pinned.
Please add a "pinmaps MAP_DIR" optional parameter as a separate patch.
> > The reason to pin program(s) is to hold some reference and to be able
> > to find them. Since we have the programs pinned we should be able to
> > find their maps with relative ease.
> >
> > $ bpftool prog show pinned /sys/fs/bpf/prog
> > 7: cgroup_skb tag 2a142ef67aaad174 gpl
> > loaded_at 2018-11-08T11:02:25-0800 uid 0
> > xlated 296B jited 229B memlock 4096B map_ids 6,7
> >
> > possibly:
> >
> > $ bpftool -j prog show pinned /sys/fs/bpf/prog | jq '.map_ids[0]'
> > 6
> >
> > Moreover, I think program and map names may collide making ELFs
> > unloadable..
> It doesn't sound like a big problem, sounds like a constraint we can live
> with.
