Re: [PATCH] libbpf: kprobe.multi: Filter with available_filter_functions_addrs

[Jiri Olsa <olsajiri@gmail.com>]

On Fri, Jun 23, 2023 at 10:12:45AM +0800, Jackie Liu wrote:

SNIP

> +
> +static void kprobe_multi_resolve_free(struct kprobe_multi_resolve *res)
> +{
> +	free(res->addrs);
> +
> +	/* reset to zero, when fallback */
> +	res->cap = 0;
> +	res->cnt = 0;
> +	res->addrs = NULL;
> +}
> +
>  struct bpf_link *
>  bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
>  				      const char *pattern,
> @@ -10477,9 +10539,16 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
>  		return libbpf_err_ptr(-EINVAL);
>  
>  	if (pattern) {
> -		err = libbpf_kallsyms_parse(resolve_kprobe_multi_cb, &res);
> -		if (err)
> -			goto error;
> +		err = libbpf_available_kprobes_parse(ftrace_resolve_kprobe_multi_cb,
> +						     &res);
> +		if (err) {
> +			/* fallback to kallsyms */
> +			kprobe_multi_resolve_free(&res);
> +			err = libbpf_kallsyms_parse(kallsyms_resolve_kprobe_multi_cb,
> +						    &res);
> +			if (err)
> +				goto error;
> +		}
>  		if (!res.cnt) {
>  			err = -ENOENT;
>  			goto error;
> @@ -10512,12 +10581,12 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
>  		goto error;
>  	}
>  	link->fd = link_fd;
> -	free(res.addrs);
> +	kprobe_multi_resolve_free(&res);

we don't need to zero res in here, so we could just leave the original
free(res.addrs) in here and perhaps rename kprobe_multi_resolve_free
to kprobe_multi_resolve_reinit

thanks,
jirka

>  	return link;
>  
>  error:
>  	free(link);
> -	free(res.addrs);
> +	kprobe_multi_resolve_free(&res);
>  	return libbpf_err_ptr(err);
>  }
>  
> -- 
> 2.25.1
>