On Tue, 2 Sept 2025 at 04:25, Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> On Mon, Sep 1, 2025 at 12:37 PM Puranjay Mohan <puranjay@xxxxxxxxxx> wrote:
> >
> > BPF streams are only valid for the main programs, to make it easier to
> > access streams from subprogs, introduce main_prog_aux in struct
> > bpf_prog_aux.
> >
> > prog->aux->main_prog_aux = prog->aux, for main programs and
> > prog->aux->main_prog_aux = main_prog->aux, for subprograms.
> >
> > This makes it easy to access streams like:
> > stream = bpf_stream_get(stream_id, prog->main_prog_aux);
> >
> > Signed-off-by: Puranjay Mohan <puranjay@xxxxxxxxxx>
> > ---
> > include/linux/bpf.h | 1 +
> > kernel/bpf/core.c | 3 +--
> > kernel/bpf/stream.c | 6 +++---
> > kernel/bpf/verifier.c | 1 +
> > 4 files changed, 6 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > index 8f6e87f0f3a89..d133171c4d2a9 100644
> > --- a/include/linux/bpf.h
> > +++ b/include/linux/bpf.h
> > @@ -1633,6 +1633,7 @@ struct bpf_prog_aux {
> > /* function name for valid attach_btf_id */
> > const char *attach_func_name;
> > struct bpf_prog **func;
> > + struct bpf_prog_aux *main_prog_aux;
> > void *jit_data; /* JIT specific data. arch dependent */
> > struct bpf_jit_poke_descriptor *poke_tab;
> > struct bpf_kfunc_desc_tab *kfunc_tab;
> > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> > index ef01cc644a965..dbbf8e4b6e4c2 100644
> > --- a/kernel/bpf/core.c
> > +++ b/kernel/bpf/core.c
> > @@ -120,6 +120,7 @@ struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flag
> >
> > fp->pages = size / PAGE_SIZE;
> > fp->aux = aux;
> > + fp->aux->main_prog_aux = aux;
>
> Though I agree that it's not strictly necessary, this approach
> is so much easier to reason about.
>
> Kumar, wdyt?
Yeah, nbd, this looks fine as well.
