Re: [PATCH HID v3 03/16] HID: bpf: implement HID-BPF through bpf_struct_ops

On Sat, Jun 8, 2024 at 2:01 AM Benjamin Tissoires bentiss@kernel.org wrote:

+static int hid_bpf_ops_init_member(const struct btf_type *t,

•                            const struct btf_member *member,
  

•                            void *kdata, const void *udata)
  

+{

•   u32 moff = __btf_member_bit_offset(t, member) / 8;
  

•   u32 flags;
  

•   switch (moff) {
  

•   case offsetof(struct hid_bpf_ops, hid_id):
  

•           /* For hid_id and flags fields, this function has to copy it
  

•            * and return 1 to indicate that the data has been handled by
  

•            * the struct_ops type, or the verifier will reject the map if
  

•            * the value of those fields is not zero.
  

•            */
  

•           ((struct hid_bpf_ops *)kdata)->hid_id = ((struct hid_bpf_ops *)udata)->hid_id;
  

•           return 1;
  

•   case offsetof(struct hid_bpf_ops, flags):
  

•           flags = ((struct hid_bpf_ops *)udata)->flags;
  

•           if (flags & ~BPF_F_BEFORE)
  

•                   return -EINVAL;
  

•           ((struct hid_bpf_ops *)kdata)->flags = flags;
  

minor nit: I'd cast kdata/udate in the beginning of the function to make the lines shorter and less verbose. Similar to how bpf_tcp_ca_init_member() does it.

Acked-by: Alexei Starovoitov ast@kernel.org