Re: [PATCH v3 net-next 1/3] perf, bpf: Add BPF support to all perf_event types

[Peter Zijlstra]

On Thu, Jun 01, 2017 at 07:03:34PM -0700, Alexei Starovoitov wrote:
> diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
> index 172dc8ee0e3b..ab93490d1a00 100644
> --- a/kernel/bpf/arraymap.c
> +++ b/kernel/bpf/arraymap.c
> @@ -452,39 +452,18 @@ static void bpf_event_entry_free_rcu(struct 
> bpf_event_entry *ee)
>  static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
>                                        struct file *map_file, int fd)
>  {
> -     const struct perf_event_attr *attr;
>       struct bpf_event_entry *ee;
> -     struct perf_event *event;
>       struct file *perf_file;
>  
>       perf_file = perf_event_get(fd);
>       if (IS_ERR(perf_file))
>               return perf_file;
>  
> -     event = perf_file->private_data;
> -     ee = ERR_PTR(-EINVAL);
> -
> -     attr = perf_event_attrs(event);
> -     if (IS_ERR(attr) || attr->inherit)
> -             goto err_out;
> -
> -     switch (attr->type) {
> -     case PERF_TYPE_SOFTWARE:
> -             if (attr->config != PERF_COUNT_SW_BPF_OUTPUT)
> -                     goto err_out;
> -             /* fall-through */
> -     case PERF_TYPE_RAW:
> -     case PERF_TYPE_HARDWARE:
> -             ee = bpf_event_entry_gen(perf_file, map_file);
> -             if (ee)
> -                     return ee;
> -             ee = ERR_PTR(-ENOMEM);
> -             /* fall-through */
> -     default:
> -             break;
> -     }

Would it make sense to call perf_event_read_local() on the events here
in order to weed out the -EOPNOTSUPP  ones?

> +     ee = bpf_event_entry_gen(perf_file, map_file);
> +     if (ee)
> +             return ee;
>  
> -err_out:
> +     ee = ERR_PTR(-ENOMEM);
>       fput(perf_file);
>       return ee;
>  }