Re: [PATCH] tools/perf: fix the word selected in find_*_bit

[Madhavan Srinivasan]

On Wednesday 15 June 2016 06:14 PM, George Spelvin wrote:
> Madhavan Srinivasan wrote:
>> +#if (__BYTE_ORDER == __BIG_ENDIAN) && (BITS_PER_LONG != 64)
>> +	tmp = addr[(((nbits - 1)/BITS_PER_LONG) - (start / BITS_PER_LONG))]
>> +								^ invert;
>> +#else
>>  	tmp = addr[start / BITS_PER_LONG] ^ invert;
>> +#endif
> Than you for diagnosing this problem, but I don't think the fix
> is correct.
>
> 1) It's not clear that all users of _find_next_bit and for_each_set_bit()
>    want this change.
> 2) Is your code even correct?  I'd think you'd want addr[x ^ 1].  Are you
>    sure you shpuld be reversing the whole array, and not just the halves of
>    each 64-bit word?
> 3) You've now broken the case of 32-bit big-endian kernel.

Yes. But looks like we havent hit this case yet. Will post a fix.

Maddy

>
> I think the proper solution is uglier than this. :-(
>