tree b8bc0f095d8de39ebca5245565a6bd4bd9585398
parent 64c179dc3d867c1fa91fa6b11cd5b84b1b10a206
author Alexei Starovoitov <ast@kernel.org> 1680309297 -0700
committer Alexei Starovoitov <ast@kernel.org> 1680309611 -0700

bpf: Refactor NULL-ness check in check_reg_type().

check_reg_type() unconditionally disallows PTR_TO_BTF_ID | PTR_MAYBE_NULL.
It's problematic for helpers that allow ARG_PTR_TO_BTF_ID_OR_NULL like
bpf_sk_storage_get(). Allow passing PTR_TO_BTF_ID | PTR_MAYBE_NULL into such
helpers. That technically includes bpf_kptr_xchg() helper, but in practice:
  bpf_kptr_xchg(..., bpf_cpumask_create());
is still disallowed because bpf_cpumask_create() returns ref counted pointer
with ref_obj_id > 0.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>