Re: [PATCH bpf-next v7 5/7] bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_cgroup_storage maps

["Leon Hwang" <leon.hwang@linux.dev>]

On Wed Sep 17, 2025 at 7:44 AM +08, Andrii Nakryiko wrote:
> On Wed, Sep 10, 2025 at 9:28 AM Leon Hwang <leon.hwang@linux.dev> wrote:
>>
>> Introduce BPF_F_ALL_CPUS flag support for percpu_cgroup_storage maps to
>> allow updating values for all CPUs with a single value for update_elem
>> API.
>>
>> Introduce BPF_F_CPU flag support for percpu_cgroup_storage maps to
>> allow:
>>
>> * update value for specified CPU for update_elem API.
>> * lookup value for specified CPU for lookup_elem API.
>>
>> The BPF_F_CPU flag is passed via map_flags along with embedded cpu info.
>>
>> Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
>> ---
>>  include/linux/bpf-cgroup.h |  4 ++--
>>  include/linux/bpf.h        |  1 +
>>  kernel/bpf/local_storage.c | 22 +++++++++++++++++++---
>>  kernel/bpf/syscall.c       |  2 +-
>>  4 files changed, 23 insertions(+), 6 deletions(-)
>>
>
> [...]
>
>> @@ -216,7 +222,7 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *key,
>>         int cpu, off = 0;
>>         u32 size;
>>
>> -       if (map_flags != BPF_ANY && map_flags != BPF_EXIST)
>> +       if ((u32)map_flags & ~(BPF_ANY | BPF_EXIST | BPF_F_CPU | BPF_F_ALL_CPUS))
>>                 return -EINVAL;
>
> shouldn't bpf_map_check_op_flags() be used here to validate cpu number
> and BPF_F_CPU and BPF_F_ALL_CPUS exclusivity?..
>

bpf_map_check_op_flags() has been called in
syscall.c::map_update_elem().

Thanks,
Leon