Re: [PATCH bpf-next] bpf: fix 'dubious one-bit signed bitfield' warnings

[Matthieu Baerts]

Hi Yonghong,

Thank you for the review!

On 10/07/2022 18:59, Yonghong Song wrote:> On 7/10/22 1:35 AM, Matthieu
Baerts wrote:
>> diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
>> index 81b19669efba..2ac424641cc3 100644
>> --- a/include/linux/bpf_verifier.h
>> +++ b/include/linux/bpf_verifier.h
>> @@ -345,10 +345,10 @@ struct bpf_verifier_state_list {
>>   };
>>     struct bpf_loop_inline_state {
>> -    int initialized:1; /* set to true upon first entry */
>> -    int fit_for_inline:1; /* true if callback function is the same
>> -                   * at each call and flags are always zero
>> -                   */
>> +    bool initialized; /* set to true upon first entry */
>> +    bool fit_for_inline; /* true if callback function is the same
>> +                  * at each call and flags are always zero
>> +                  */
> 
> I think changing 'int' to 'unsigned' is a better alternative for
> potentially adding more bitfields in the future. This is also a pattern
> for many other kernel data structures.

There was room, I was not sure if it would be OK but I saw 'bool' were
often used in structures from this bpf_verifier.h file.

I can of course switch to an unsigned one. I would have picked 'u8' when
looking at the structures around but any preferences from you?
'unsigned', 'unsigned int', 'u8', 'u32'?

Cheers,
Matt
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