Re: [bpf PATCH 1/2] bpf, sockmap: fix sk->prot unhash op reset

John Fastabend
2021-03-26T00:58:32Z

Cong Wang wrote:
> On Wed, Mar 24, 2021 at 7:28 PM John Fastabend <john.fastabend@gmail.com> wrote:
> >
> > Cong Wang wrote:
> > > On Wed, Mar 24, 2021 at 1:59 PM John Fastabend <john.fastabend@gmail.com> wrote:
> > > > diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
> > > > index 47b7c5334c34..ecb5634b4c4a 100644
> > > > --- a/net/tls/tls_main.c
> > > > +++ b/net/tls/tls_main.c
> > > > @@ -754,6 +754,12 @@ static void tls_update(struct sock *sk, struct proto *p,
> > > >
> > > > ctx = tls_get_ctx(sk);
> > > > if (likely(ctx)) {
> > > > + /* TLS does not have an unhash proto in SW cases, but we need
> > > > + * to ensure we stop using the sock_map unhash routine because
> > > > + * the associated psock is being removed. So use the original
> > > > + * unhash handler.
> > > > + */
> > > > + WRITE_ONCE(sk->sk_prot->unhash, p->unhash);
> > > > ctx->sk_write_space = write_space;
> > > > ctx->sk_proto = p;
> > >
> > > It looks awkward to update sk->sk_proto inside tls_update(),
> > > at least when ctx!=NULL.
> >
> > hmm. It doesn't strike me as paticularly awkward but OK.
>
> I read tls_update() as "updating ctx when it is initialized", with your
> patch, we are updating sk->sk_prot->unhash too when updating ctx,
> pretty much like a piggyback, hence it reads odd to me.
>
> Thanks.

OK convinced.