Re: [PATCH bpf-next v7 01/11] bpf: add bpf_func_t and trampoline helpers

[Stanislav Fomichev <sdf@google.com>]

On Thu, May 19, 2022 at 5:45 PM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 5/18/22 3:55 PM, Stanislav Fomichev wrote:
> > I'll be adding lsm cgroup specific helpers that grab
> > trampoline mutex.
> >
> > No functional changes.
> >
> > Signed-off-by: Stanislav Fomichev <sdf@google.com>
> > ---
> >   include/linux/bpf.h     | 11 ++++----
> >   kernel/bpf/trampoline.c | 62 ++++++++++++++++++++++-------------------
> >   2 files changed, 38 insertions(+), 35 deletions(-)
> >
> [...]
> > +
> > +int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
> > +{
> > +     int err;
> > +
> > +     mutex_lock(&tr->mutex);
> > +     err = __bpf_trampoline_link_prog(link, tr);
> >       mutex_unlock(&tr->mutex);
> >       return err;
> >   }
> >
> >   /* bpf_trampoline_unlink_prog() should never fail. */
>
> The comment here can be removed.

Will do, thank you!


> > -int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
> > +static int __bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
> >   {
> >       enum bpf_tramp_prog_type kind;
> >       int err;
> >
> >       kind = bpf_attach_type_to_tramp(link->link.prog);
> > -     mutex_lock(&tr->mutex);
> >       if (kind == BPF_TRAMP_REPLACE) {
> >               WARN_ON_ONCE(!tr->extension_prog);
> >               err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP,
> >                                        tr->extension_prog->bpf_func, NULL);
> >               tr->extension_prog = NULL;
> > -             goto out;
> > +             return err;
> >       }
> >       hlist_del_init(&link->tramp_hlist);
> >       tr->progs_cnt[kind]--;
> > -     err = bpf_trampoline_update(tr);
> > -out:
> > +     return bpf_trampoline_update(tr);
> > +}
> > +
> > +/* bpf_trampoline_unlink_prog() should never fail. */
> > +int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
> > +{
> > +     int err;
> > +
> > +     mutex_lock(&tr->mutex);
> > +     err = __bpf_trampoline_unlink_prog(link, tr);
> >       mutex_unlock(&tr->mutex);
> >       return err;
> >   }