Re: [PATCH bpf-next 2/5] bpf: Implement cgroup storage available to non-cgroup-attached bpf progs

[Martin KaFai Lau <martin.lau@linux.dev>]

On 10/18/22 10:17 AM, Alexei Starovoitov wrote:
> On Tue, Oct 18, 2022 at 10:08 AM <sdf@google.com> wrote:
>>>>
>>>> '#define BPF_MAP_TYPE_CGROUP_STORAGE BPF_MAP_TYPE_CGRP_LOCAL_STORAGE /*
>>>> depreciated by BPF_MAP_TYPE_CGRP_STORAGE */' in the uapi.
>>>>
>>>> The new cgroup storage uses a shorter name "cgrp", like
>>>> BPF_MAP_TYPE_CGRP_STORAGE and bpf_cgrp_storage_get()?
>>
>>> This might work and the naming convention will be similar to
>>> existing sk/inode/task storage.
>>
>> +1, CGRP_STORAGE sounds good!
> 
> +1 from me as well.
> 
> Something like this ?
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 17f61338f8f8..13dcb2418847 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -922,7 +922,8 @@ enum bpf_map_type {
>          BPF_MAP_TYPE_CPUMAP,
>          BPF_MAP_TYPE_XSKMAP,
>          BPF_MAP_TYPE_SOCKHASH,
> -       BPF_MAP_TYPE_CGROUP_STORAGE,
> +       BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED,
> +       BPF_MAP_TYPE_CGROUP_STORAGE = BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED,

+1

>          BPF_MAP_TYPE_REUSEPORT_SOCKARRAY,
>          BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE,
>          BPF_MAP_TYPE_QUEUE,
> @@ -935,6 +936,7 @@ enum bpf_map_type {
>          BPF_MAP_TYPE_TASK_STORAGE,
>          BPF_MAP_TYPE_BLOOM_FILTER,
>          BPF_MAP_TYPE_USER_RINGBUF,
> +       BPF_MAP_TYPE_CGRP_STORAGE,
>   };
> 
> What are we going to do with BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE ?
> Probably should come up with a replacement as well?

Yeah, need to come up with a percpu answer for it.  The percpu usage has never 
come up on the sk storage and also the later task/inode storage.  or the user is 
just getting by with an array like map's value.

May be the bpf prog can call bpf_mem_alloc() to alloc the percpu memory in the 
future and then store it as the kptr in the BPF_MAP_TYPE_CGRP_STORAGE?