On 2025/11/26 23:11, [email protected] wrote:
>> diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
>> index aedf573bd..013f4db99 100644
>> --- a/include/linux/bpf-cgroup.h
>> +++ b/include/linux/bpf-cgroup.h
>
> [ ... ]
>
>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>> index f79d2ae27..9e756db5e 100644
>> --- a/include/linux/bpf.h
>> +++ b/include/linux/bpf.h
>
> [ ... ]
>
>> diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
>> index 2ab4b60ff..1ccbf28b2 100644
>> --- a/kernel/bpf/local_storage.c
>> +++ b/kernel/bpf/local_storage.c
>> @@ -180,7 +180,7 @@ static long cgroup_storage_update_elem(struct bpf_map
>> *map, void *key,
>> }
>>
>> int bpf_percpu_cgroup_storage_copy(struct bpf_map *_map, void *key,
>> - void *value)
>> + void *value, u64 map_flags)
>> {
>> struct bpf_cgroup_storage_map *map = map_to_storage(_map);
>> struct bpf_cgroup_storage *storage;
>> @@ -198,11 +198,17 @@ int bpf_percpu_cgroup_storage_copy(struct bpf_map
>> *_map, void *key,
>> * access 'value_size' of them, so copying rounded areas
>> * will not leak any kernel data
>> */
>> + if (map_flags & BPF_F_CPU) {
>> + cpu = map_flags >> 32;
>> + copy_map_value(_map, value, per_cpu_ptr(storage->percpu_buf,
>> cpu));
>> + goto unlock;
>> + }
>
> Should check_and_init_map_value() be called here after copy_map_value()?
>
It should not be called, because percpu_cgroup_storage maps do not
support any special fields.
Thanks,
Leon
> The similar implementations in bpf_percpu_array_copy() and
> bpf_percpu_hash_copy() both call check_and_init_map_value() after
> copying a single CPU's value when BPF_F_CPU is set:
>
> bpf_percpu_array_copy():
> if (map_flags & BPF_F_CPU) {
> cpu = map_flags >> 32;
> copy_map_value(map, value, per_cpu_ptr(pptr, cpu));
> check_and_init_map_value(map, value);
> goto unlock;
> }
>
> bpf_percpu_hash_copy():
> if (map_flags & BPF_F_CPU) {
> cpu = map_flags >> 32;
> copy_map_value(map, value, per_cpu_ptr(pptr, cpu));
> check_and_init_map_value(map, value);
> goto out;
> }
>
> The check_and_init_map_value() call initializes special BTF fields
> (timers, kptrs, etc.) when copying map values to userspace. Without it,>
> these fields might not be properly initialized if percpu_cgroup_storage
> map values contain such fields.
>
>> size = round_up(_map->value_size, 8);
>> for_each_possible_cpu(cpu) {
>> copy_map_value_long(_map, value + off,
>> per_cpu_ptr(storage->percpu_buf, cpu));
>> off += size;
>> }
>> +unlock:
>> rcu_read_unlock();
>> return 0;
>> }
>
> [ ... ]
>
>
> ---
> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
>
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/19708012130
