Re: [PATCHv5 bpf-next 13/28] bpf: Add support for tracing multi link

[Jiri Olsa <olsajiri@gmail.com>]

On Sat, Apr 18, 2026 at 08:58:39AM +0000, sashiko-bot@kernel.org wrote:
> Sashiko AI review found 1 potential issue(s):
> - [Low] The patch references several undeclared identifiers and incomplete types, causing compilation failures.
> --
> 
> commit fc7697083b71bebef41d2da3a91ca2a0741ad6f0
> Author: Jiri Olsa <jolsa@kernel.org>
> 
> bpf: Add support for tracing multi link
> 
> Adding a new link to allow attaching a BPF program to multiple function
> BTF IDs, represented by struct bpf_tracing_multi_link.
> 
> > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > index a3c0214ca9341..da3e01dd7ee9a 100644
> > --- a/kernel/bpf/syscall.c
> > +++ b/kernel/bpf/syscall.c
> [ ... ]
> > @@ -5748,6 +5748,8 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr)
> >  			ret = bpf_iter_link_attach(attr, uattr, prog);
> >  		else if (prog->expected_attach_type == BPF_LSM_CGROUP)
> >  			ret = cgroup_bpf_link_attach(attr, prog);
> > +		else if (is_tracing_multi(prog->expected_attach_type))
> > +			ret = bpf_tracing_multi_attach(prog, attr);
> 
> Is is_tracing_multi() defined anywhere? It doesn't appear to be declared
> in this patch or the existing kernel tree, which could lead to a build
> failure.

it's added in "bpf: Add multi tracing attach types"

> 
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index af7079aa0f36d..df06a733a2e71 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> [ ... ]
> > +static void bpf_tracing_multi_link_release(struct bpf_link *link)
> > +{
> > +	struct bpf_tracing_multi_link *tr_link =
> > +		container_of(link, struct bpf_tracing_multi_link, link);
> > +
> > +	WARN_ON_ONCE(bpf_trampoline_multi_detach(link->prog, tr_link));
> > +}
> 
> Where is struct bpf_tracing_multi_link defined? It seems to be an
> incomplete type here. 
> 
> Similarly, bpf_trampoline_multi_detach() doesn't appear to be declared in
> this patch. Will this cause compilation errors when dereferencing or
> calling these?

defined in previous patch "bpf: Add bpf_trampoline_multi_attach/detach functions"

> 
> [ ... ]
> > +	err = bpf_link_prime(&link->link, &link_primer);
> > +	if (err)
> > +		goto error;
> > +
> > +	link->nodes_cnt = cnt;
> > +
> > +	err = bpf_trampoline_multi_attach(prog, ids, link);
> 
> Does bpf_trampoline_multi_attach() also miss a declaration?

defined in previous patch "bpf: Add bpf_trampoline_multi_attach/detach functions"

what do I miss? ;-)

jirka