Re: [Xen-devel] [PATCH v3 03/13] xen: introduce cpumask_from_bitmap

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.04.13 at 12:01, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
wrote:
> On Thu, 25 Apr 2013, Jan Beulich wrote:
>> >>> On 24.04.13 at 21:07, Stefano Stabellini 
>> >>> <stefano.stabellini@xxxxxxxxxxxxx> 
> wrote:
>> > +static inline cpumask_t cpumask_from_bitmap(unsigned long *bits, int 
> nr_bits)
>> > +{
>> > +    cpumask_t mask;
>> > +    int len = nr_bits < nr_cpumask_bits ? nr_bits : nr_cpumask_bits;
>> 
>> min(nr_bits, nr_cpumask_bits)
>> 
>> > +
>> > +    memset(&mask, 0x00, sizeof(mask));
>> 
>> bitmap_zero().
>> 
>> > +  bitmap_copy(mask.bits, bits, len);
>> 
>> Hard tab.
>> 
>> > +
>> > +    return mask;
>> > +}
>> 
>> And most importantly: Why? This isn't an operation that should
>> commonly be done, and hence having a utility function for this
>> seems to invite for abuse rather than really help.
> 
> TBH I have done it to address Ian's comment, I don't have a strong
> opinion on this.
> However it is true that from an API point of view, cpumask_from_bitmap
> allows us to cover the new use case without breaking the cpumask
> abstraction.

Rather than adding a new abstraction that's used for a single
special case, and if open coding is undesirable, I'd prefer if you
used bitmap_to_xenctl_bitmap() plus xenctl_bitmap_to_cpumask()
if at all possible.

Jan


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