Re: [PATCH bpf-next 3/7] bpf: Register and unregister a struct_ops by their bpf_links.

[Kui-Feng Lee <sinquersw@gmail.com>]

On 2/16/23 14:38, Martin KaFai Lau wrote:
> On 2/16/23 8:42 AM, Kui-Feng Lee wrote:
>>>> @@ -638,6 +647,8 @@ static struct bpf_map 
>>>> *bpf_struct_ops_map_alloc(union bpf_attr *attr)
>>>>       set_vm_flush_reset_perms(st_map->image);
>>>>       bpf_map_init_from_attr(map, attr);
>>>> +    map->map_flags |= attr->map_flags & BPF_F_LINK;
>>>
>>> This should have already been done in bpf_map_init_from_attr().
>>
>> bpf_map_init_from_attr() will filter out all flags except BPF_F_RDONLY 
>> & BPF_F_WRONLY.
> 
> should be the opposite:
> 
> static u32 bpf_map_flags_retain_permanent(u32 flags)
> {
>      /* Some map creation flags are not tied to the map object but
>           * rather to the map fd instead, so they have no meaning upon
>           * map object inspection since multiple file descriptors with
>           * different (access) properties can exist here. Thus, given
>           * this has zero meaning for the map itself, lets clear these
>           * from here.
>           */
>      return flags & ~(BPF_F_RDONLY | BPF_F_WRONLY);
> }

Got it! Thank you!