Re: [git pull] cpus4096 fixes

[Mike Travis <travis@sgi.com>]

Ingo Molnar wrote:
> * Linus Torvalds <torvalds@linux-foundation.org> wrote:
> 
>>
>> On Mon, 28 Jul 2008, Linus Torvalds wrote:
>>> Here's a trivial setup, that is even tested. It's _small_ too.
>>>
>>> 	/* cpu_bit_bitmap[0] is empty - so we can back into it */
>>> 	#define MASK_DECLARE_1(x) [x+1][0] = 1ul << (x)
>>> 	#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
>>> 	#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
>>> 	#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
>>>
>>> 	static const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
>>> 		MASK_DECLARE_8(0), MASK_DECLARE_8(8),
>>> 		MASK_DECLARE_8(16), MASK_DECLARE_8(24),
>>> 	#if BITS_PER_LONG > 32
>>> 		MASK_DECLARE_8(32), MASK_DECLARE_8(40),
>>> 		MASK_DECLARE_8(48), MASK_DECLARE_8(56),
>>> 	#endif
>>> 	};
>>>
>>> 	static inline const cpumask_t *get_cpu_mask(unsigned int nr)
>>> 	{
>>> 		const unsigned long *p = cpu_bit_bitmap[1 + nr % BITS_PER_LONG];
>>> 		p -= nr / BITS_PER_LONG;
>>> 		return (const cpumask_t *)p;
>>> 	}
>> Btw, Ingo, can we get this issue resolved asap, please?
>>
>> I was planning on doing -rc1 today, but this kind of hangs over me. 
>> The above three lines of code (and more lines of macro initializers) 
>> obviously does need some more testing, but if you hook it into the 
>> other changes you already had, maybe we can get it done.
>>
>> Hmm?
> 
> yeah, i'm on it. If everything goes well hopefully i'll have something 
> pullable in 1-2 hours, if that's ok as a timeframe.
> 
> 	Ingo

One problem is that the current api is cpumask_t cpumask_of_cpu(x), so
all ref's would have to be changed.  (Unless there's some clever way of
defining "&cpumask_of_cpu(x)" to be get_cpu_mask(x) ...?)

Do you want me to do these changes?

Thanks,
Mike