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

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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.




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