Tejun> 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.
Tejun> Violently seconded. How about it be made into a real function instead? I was reading through the patch, but got timed out yesterday, so take this with a grain of salt. I thought I saw a couple of macros defined to use this macro yet again. Which I figured might be a problem is the passed in variables get munged. In any case, why does something so complicated need to be a macro, why not a function instead? John - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
