On 1/2/25 10:14 PM, Eduard Zingerman wrote:
It was a bit hard for me to figure out what went wrong from the description,
could you please double-check my understanding below?
- when struct_ops program is attached,
bpf_struct_ops_map_update_elem() scans every member of specific
struct_ops type (e.g. struct tcp_congestion_ops) looking for fields
with type 'struct module *';
- to find these fields BTF id of 'struct module' is used, this id does
not exist when CONFIG_MODULES=n, bpf_struct_ops_map_update_elem()
does not check if 'struct module' BTF id is non-zero;
- bpf_struct_ops_map_update_elem() initializes 'struct module *'
fields using a magic value BPF_MODULE_OWNER, this initialization
would not happen if fields are not found;
Thanks for reviewing and testing it!
Yes, the understanding is correct. These are pretty much the only two places
where st_ops_ids[IDX_MODULE_ID] and BPF_MODULE_OWNER are used.
