On Thu, Jan 3, 2019 at 11:43 AM Jakub Kicinski
<jakub.kicin...@netronome.com> wrote:
>
> On Thu, 3 Jan 2019 10:33:05 -0800, Stanislav Fomichev wrote:
> > Bpftool expects both key and value for 'update' operations. For some
> > map types, key should not be specified. Support updating those map types.
> >
> > Before:
> > bpftool map create /sys/fs/bpf/q type queue value 4 entries 10 name q
> > bpftool map update pinned /sys/fs/bpf/q value 0 1 2 3
> > Error: did not find key
> >
> > After:
> > bpftool map create /sys/fs/bpf/q type queue value 4 entries 10 name q
> > bpftool map update pinned /sys/fs/bpf/q value 0 1 2 3
> >
> > Signed-off-by: Stanislav Fomichev <s...@google.com>
>
> I guess it doesn't hurt to fix update/lookup, but I'd prefer to see new
> separate subcommands to be honest :(
>
> bpftool map push/pop/peek
>
> Could you add those as well? I think most users will be more familiar
> with the helpers than the fact that the syscall reuses the old commands.
Sure, I thought about that, but decided to mirror syscall interface initially.
I can do both: support update/lookup and add new commands.
>
> > diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
> > index 2037e3dc864b..30b92715248d 100644
> > --- a/tools/bpf/bpftool/map.c
> > +++ b/tools/bpf/bpftool/map.c
> > @@ -781,11 +781,11 @@ static int do_dump(int argc, char **argv)
> >
> > static int do_update(int argc, char **argv)
> > {
> > + void *key = NULL, *value = NULL;
>
> nit: it seems tiny bit more readable to init these in the place you'd
> otherwise set key to malloc (in an else clause)
Ack, will do.
>
> > struct bpf_map_info info = {};
> > __u32 len = sizeof(info);
> > __u32 *value_fd = NULL;
> > __u32 flags = BPF_ANY;
> > - void *key, *value;
> > int fd, err;
> >
> > if (argc < 2)
> > @@ -795,9 +795,16 @@ static int do_update(int argc, char **argv)
> > if (fd < 0)
> > return -1;
> >
> > - key = malloc(info.key_size);
> > + if (info.key_size) {
> > + key = malloc(info.key_size);
> > + if (!key) {
> > + p_err("mem alloc failed");
> > + err = -1;
> > + goto exit_free;
> > + }
> > + }
> > value = alloc_value(&info);
>
> Would you mind taking care of the value as well? So we are ready if
> sets are ever added?
Sure, makes sense.
>
> > - if (!key || !value) {
> > + if (!value) {
> > p_err("mem alloc failed");
> > err = -1;
> > goto exit_free;
>
> I'd consider this -next material TBH, but not strongly.
My initial thought that these two can go into bpf as 'fixes' because
they technically don't add any new features.
But I'm fine with -next as well, I'll prepare a v2 for bpf-next with
those two changes plus push/pop/peek.
Thank you for a review!
