Re: [bpf-next v3 1/2] bpftool: Add auto_attach for bpf prog load|loadall

[wangyufen]

在 2022/9/9 19:38, Quentin Monnet 写道:
> On 09/09/2022 06:53, Wang Yufen wrote:
> > Add auto_attach optional to support one-step load-attach-pin_link.
> >
> > For example,
> >     $ bpftool prog loadall test.o /sys/fs/bpf/test auto_attach
> >
> >     $ bpftool link
> >     26: tracing  name test1  tag f0da7d0058c00236  gpl
> >     	loaded_at 2022-09-09T21:39:49+0800  uid 0
> >     	xlated 88B  jited 55B  memlock 4096B  map_ids 3
> >     	btf_id 55
> >     28: kprobe  name test3  tag 002ef1bef0723833  gpl
> >     	loaded_at 2022-09-09T21:39:49+0800  uid 0
> >     	xlated 88B  jited 56B  memlock 4096B  map_ids 3
> >     	btf_id 55
> >     57: tracepoint  name oncpu  tag 7aa55dfbdcb78941  gpl
> >     	loaded_at 2022-09-09T21:41:32+0800  uid 0
> >     	xlated 456B  jited 265B  memlock 4096B  map_ids 17,13,14,15
> >     	btf_id 82
> >
> >     $ bpftool link
> >     1: tracing  prog 26
> >     	prog_type tracing  attach_type trace_fentry
> >     3: perf_event  prog 28
> >     10: perf_event  prog 57
> >
> > The auto_attach optional can support tracepoints, k(ret)probes,
> > u(ret)probes.
> >
> > Signed-off-by: Wei Yongjun <weiyongjun1@xxxxxxxxxx>
> > Signed-off-by: Wang Yufen <wangyufen@xxxxxxxxxx>
> Thanks, looks better! I just have some minor comments, please see inline
> below.
>
> > ---
> > v2 -> v3: switch to extend prog load command instead of extend perf
> > v2: https://patchwork.kernel.org/project/netdevbpf/patch/20220824033837.458197-1-weiyongjun1@xxxxxxxxxx/
> > v1: https://patchwork.kernel.org/project/netdevbpf/patch/20220816151725.153343-1-weiyongjun1@xxxxxxxxxx/
> >   tools/bpf/bpftool/prog.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++--
> >   1 file changed, 74 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
> > index c81362a..853a73e 100644
> > --- a/tools/bpf/bpftool/prog.c
> > +++ b/tools/bpf/bpftool/prog.c
> > @@ -1453,6 +1453,68 @@ static int do_run(int argc, char **argv)
> >   	return ret;
> >   }
> >   
> > +static int
> > +do_prog_attach_pin(struct bpf_program *prog, const char *path)
> Can we rename this function please? The pattern "do_...()" looks like
> one of the names for the functions we use for the subcommands via the
> struct cmd. Maybe auto_attach_program()?
>
> > +{
> > +	struct bpf_link *link = NULL;
> Nit: No need to initialise link
>
> > +	int err;
> > +
> > +	link = bpf_program__attach(prog);
> > +	err = libbpf_get_error(link);
> > +	if (err)
> > +		return err;
> > +
> > +	err = bpf_link__pin(link, path);
> > +	if (err) {
> > +		bpf_link__destroy(link);
> > +		return err;
> > +	}
> > +	return 0;
> > +}
> > +
> > +static int pathname_concat(const char *path, const char *name, char *buf)
> > +{
> > +	int len;
> > +
> > +	len = snprintf(buf, PATH_MAX, "%s/%s", path, name);
> > +	if (len < 0)
> > +		return -EINVAL;
> > +	else if (len >= PATH_MAX)
> Nit: "else" not necessary, you returned if len < 0.
>
> > +		return -ENAMETOOLONG;
> > +
> > +	return 0;
> > +}
> > +
> > +static int
> > +do_obj_attach_pin_programs(struct bpf_object *obj, const char *path)
> Same, can we rename this function please?
>
> > +{
> > +	struct bpf_program *prog;
> > +	char buf[PATH_MAX];
> > +	int err;
> > +
> > +	bpf_object__for_each_program(prog, obj) {
> > +		err = pathname_concat(path, bpf_program__name(prog), buf);
> > +		if (err)
> > +			goto err_unpin_programs;
> > +
> > +		err = do_prog_attach_pin(prog, buf);
> > +		if (err)
> > +			goto err_unpin_programs;
> > +	}
> > +
> > +	return 0;
> > +
> > +err_unpin_programs:
> > +	while ((prog = bpf_object__prev_program(obj, prog))) {
> > +		if (pathname_concat(path, bpf_program__name(prog), buf))
> > +			continue;
> > +
> > +		bpf_program__unpin(prog, buf);
> > +	}
> > +
> > +	return err;
> > +}
> > +
> >   static int load_with_options(int argc, char **argv, bool first_prog_only)
> >   {
> >   	enum bpf_prog_type common_prog_type = BPF_PROG_TYPE_UNSPEC;
> > @@ -1464,6 +1526,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
> >   	struct bpf_program *prog = NULL, *pos;
> >   	unsigned int old_map_fds = 0;
> >   	const char *pinmaps = NULL;
> > +	bool auto_attach = false;
> >   	struct bpf_object *obj;
> >   	struct bpf_map *map;
> >   	const char *pinfile;
> > @@ -1583,6 +1646,9 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
> >   				goto err_free_reuse_maps;
> >   
> >   			pinmaps = GET_ARG();
> > +		} else if (is_prefix(*argv, "auto_attach")) {
> > +			auto_attach = true;
> > +			NEXT_ARG();
> >   		} else {
> >   			p_err("expected no more arguments, 'type', 'map' or 'dev', got: '%s'?",
> >   			      *argv);
> > @@ -1692,14 +1758,20 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
> >   			goto err_close_obj;
> >   		}
> >   
> > -		err = bpf_obj_pin(bpf_program__fd(prog), pinfile);
> > +		if (auto_attach)
> > +			err = do_prog_attach_pin(prog, pinfile);
> > +		else
> > +			err = bpf_obj_pin(bpf_program__fd(prog), pinfile);
> >   		if (err) {
> >   			p_err("failed to pin program %s",
> >   			      bpf_program__section_name(prog));
> >   			goto err_close_obj;
> >   		}
> >   	} else {
> > -		err = bpf_object__pin_programs(obj, pinfile);
> > +		if (auto_attach)
> > +			err = do_obj_attach_pin_programs(obj, pinfile);
> > +		else
> > +			err = bpf_object__pin_programs(obj, pinfile);
> >   		if (err) {
> >   			p_err("failed to pin all programs");
> >   			goto err_close_obj;
> Please update the usage string in do_help() at the end of the file.

Thanks for your comments.
All will do in v4.