netdev - Re: [PATCH v2 1/3] bpf: allow zero-initializing hash map seed

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Message-ID: <CAPhsuW5WW6RQG5F3O2a9YwLAue5Ng1gPmtMuqzG9n5pB=D3xsQ@mail.gmail.com>
Date:   Tue, 6 Nov 2018 16:39:14 -0800
From:   Song Liu <liu.song.a23@...il.com>
To:     lmb@...udflare.com
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Networking <netdev@...r.kernel.org>, linux-api@...r.kernel.org
Subject: Re: [PATCH v2 1/3] bpf: allow zero-initializing hash map seed

On Thu, Oct 25, 2018 at 8:12 AM Lorenz Bauer <lmb@...udflare.com> wrote:
>
> On Tue, 9 Oct 2018 at 01:08, Song Liu <liu.song.a23@...il.com> wrote:
> >
> > > --- a/include/uapi/linux/bpf.h
> > > +++ b/include/uapi/linux/bpf.h
> > > @@ -253,6 +253,8 @@ enum bpf_attach_type {
> > >  #define BPF_F_NO_COMMON_LRU    (1U << 1)
> > >  /* Specify numa node during map creation */
> > >  #define BPF_F_NUMA_NODE                (1U << 2)
> > > +/* Zero-initialize hash function seed. This should only be used for testing. */
> > > +#define BPF_F_ZERO_SEED                (1U << 6)
> >
> > Please add this line after
> > #define BPF_F_STACK_BUILD_ID    (1U << 5)
>
> I wanted to keep the flags for BPF_MAP_CREATE grouped together.
> Maybe the correct value is (1U << 3)? It seemed like the other flags
> were allocated to avoid
> overlap between different BPF commands, however, so I tried to follow suit.

I think it should be (1U << 6). We probably should move BPF_F_QUERY_EFFECTIVE
to after BPF_F_STACK_BUILD_ID (and BPF_F_ZERO_SEED).

Also, please rebase against the latest bpf-next tree and resubmit the set.

Thanks,
Song