Re: [PATCH bpf-next] bpf: use type_may_be_null() helper for nullable-param check

[Eduard Zingerman]

On Thu, 2024-09-05 at 13:52 +0800, Shung-Hsi Yu wrote:
> Commit 980ca8ceeae6 ("bpf: check bpf_dummy_struct_ops program params for
> test runs") does bitwise AND between reg_type and PTR_MAYBE_NULL, which
> is correct, but due to type difference the compiler complains:
> 
>   net/bpf/bpf_dummy_struct_ops.c:118:31: warning: bitwise operation between different enumeration types ('const enum bpf_reg_type' and 'enum bpf_type_flag') [-Wenum-enum-conversion]
>     118 |                 if (info && (info->reg_type & PTR_MAYBE_NULL))
>         |                              ~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~
> 
> Workaround the warning by moving the type_may_be_null() helper from
> verifier.c into bpf_verifier.h, and reuse it here to check whether param
> is nullable.
> 
> Fixes: 980ca8ceeae6 ("bpf: check bpf_dummy_struct_ops program params for test runs")
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Closes: https://lore.kernel.org/oe-kbuild-all/202404241956.HEiRYwWq-lkp@xxxxxxxxx/
> Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@xxxxxxxx>
> ---

Thank you for this fix.
Replacing other uses of PTR_MAYBE_NULL suggested by Matt seems like a
good idea, but it does not preclude merge for this patch.

Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>

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