Avi Kivity wrote:
> NeilBrown wrote:
>> To achieve this, the "for_each" macros are now somewhat more complex.
>> For example, rq_for_each_segment is:
>>
>> #define bio_for_each_segment_offset(bv, bio, _i, offs, _size) \
>> for (_i.i = 0, _i.offset = (bio)->bi_offset + offs, \
>> _i.size = min_t(int, _size, (bio)->bi_size - offs); \
>> _i.i < (bio)->bi_vcnt && _i.size > 0; \
>> _i.i++) \
>> if (bv = *bio_iovec_idx((bio), _i.i), \
>> bv.bv_offset += _i.offset, \
>> bv.bv_len <= _i.offset \
>> ? (_i.offset -= bv.bv_len, 0) \
>> : (bv.bv_len -= _i.offset, \
>> _i.offset = 0, \
>> bv.bv_len < _i.size \
>> ? (_i.size -= bv.bv_len, 1) \
>> : (bv.bv_len = _i.size, \
>> _i.size = 0, \
>> bv.bv_len > 0)))
>>
>> #define bio_for_each_segment(bv, bio, __i) \
>> bio_for_each_segment_offset(bv, bio, __i, 0, (bio)->bi_size)
>>
>> It does some with some explanatory text in a comment, but it is still
>> a bit daunting. Any suggestions on making this more approachable
>> would be very welcome.
>>
>>
>
> Well, I hesitate to state the obvious, but how about:
>
> #define bio_for_each_segment_offset(bv, bio, _i, offs, _size) \
> for (bio_iterator_init(&_i, ...); bio_iterator_cont(&_i, ...);
> bio_iterator_advance(&_i, ...)) \
> if (bio_iterator_want_segment(&_i, ...))
>
> While this doesn't remove the complexity, at least it's readable.
Violently seconded.
--
tejun
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