Re: [PATCH v3 bpf-next 1/2] bpf: af_unix: Implement BPF iterator for UNIX domain socket.

[Kuniyuki Iwashima <kuniyu@amazon.co.jp>]

From:   Yonghong Song <yhs@fb.com>
Date:   Thu, 5 Aug 2021 09:53:40 -0700
> On 8/4/21 12:08 AM, Kuniyuki Iwashima wrote:
> > This patch implements the BPF iterator for the UNIX domain socket and
> > exports some functions under GPL for the CONFIG_UNIX=m case.
> > 
> > Currently, the batch optimization introduced for the TCP iterator in the
> > commit 04c7820b776f ("bpf: tcp: Bpf iter batching and lock_sock") is not
> > applied.  It will require replacing the big lock for the hash table with
> > small locks for each hash list not to block other processes.
> > 
> > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
> > ---
> >   fs/proc/proc_net.c      |  2 +
> >   include/linux/btf_ids.h |  3 +-
> >   kernel/bpf/bpf_iter.c   |  3 ++
> >   net/core/filter.c       |  1 +
> >   net/unix/af_unix.c      | 93 +++++++++++++++++++++++++++++++++++++++++
> >   5 files changed, 101 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
> > index 15c2e55d2ed2..887a8102da9f 100644
> > --- a/fs/proc/proc_net.c
> > +++ b/fs/proc/proc_net.c
> > @@ -91,6 +91,7 @@ int bpf_iter_init_seq_net(void *priv_data, struct bpf_iter_aux_info *aux)
> >   #endif
> >   	return 0;
> >   }
> > +EXPORT_SYMBOL_GPL(bpf_iter_init_seq_net);
> 
> bpf_iter does not support modules for now as it is implemented before 
> module btf support. It needs some changes.
> For example, currently bpf_iter only caches/uses the vmlinux btf_id
> and module obj_id and module btf_id is not used.
> One example is ipv6 and bpf_iter is guarded with IS_BUILTIN(CONFIG_IPV6).
> 
> So you could (1) add btf_iter support module btf in this patch set, or
> (2). check IS_BUILTIN(CONFIG_UNIX). (2) might be easier and you can have
> a subsequent patch set to add module support for bpf_iter. But it is
> up to you.

I'll add IS_BUILTIN() check in the next spin and give a try to (1).
Thanks for review!