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

[wangyufen <wangyufen@huawei.com>]

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@huawei.com>
>> Signed-off-by: Wang Yufen <wangyufen@huawei.com>
> 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@huawei.com/
>> v1: https://patchwork.kernel.org/project/netdevbpf/patch/20220816151725.153343-1-weiyongjun1@huawei.com/
>>   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.