Hi, Alexei: On 2022/11/28 08:44, Alexei Starovoitov wrote: > On Sat, Nov 26, 2022 at 2:54 AM Hengqi Chen <hengqi.chen@xxxxxxxxx> wrote: >> >> The timer_off value could be -EINVAL or -ENOENT when map value of >> inner map is struct and contains no bpf_timer. The EINVAL case happens >> when the map is created without BTF key/value info, map->timer_off >> is set to -EINVAL in map_create(). The ENOENT case happens when >> the map is created with BTF key/value info (e.g. from BPF skeleton), >> map->timer_off is set to -ENOENT as what btf_find_timer() returns. >> In bpf_map_meta_equal(), we expect timer_off to be equal even if >> map value does not contains bpf_timer. This rejects map_in_map created >> with BTF key/value info to be updated using inner map without BTF >> key/value info in case inner map value is struct. This commit lifts >> such restriction. > > Sorry, but I prefer to label this issue as 'wont-fix'. > Mixing BTF enabled and non-BTF inner maps is a corner case We do have such usecase. The BPF progs and maps are pinned to bpffs using BPF object file. And the map_in_map is updated by some other process which don't have access to such BTF info. > that is not worth fixing. Is there a way to get this fixed for v5.x series only ? > At some point we will require all programs and maps to contain BTF. > It's necessary for introspection. We don't care much about BTF for introspection. In production, we always have a version field and some reserved fields in the map value for backward compatibility. The interpretation of such map values are left to upper layer. > The maps as blobs of data should not be used. > Much so adding support for mixed use as inner maps.
