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Subject: Re: [PATCH v19 3/7] xbitmap: add more operations
On 12/15/2017 12:29 AM, Tetsuo Handa wrote:
Wei Wang wrote:I used the example of xb_clear_bit_range(), and xb_find_next_bit() is the same fundamentally. Please let me know if anywhere still looks fuzzy.I don't think it is the same for xb_find_next_bit() with set == 0. + if (radix_tree_exception(bmap)) { + unsigned long tmp = (unsigned long)bmap; + unsigned long ebit = bit + 2; + + if (ebit >= BITS_PER_LONG) + continue; + if (set) + ret = find_next_bit(&tmp, BITS_PER_LONG, ebit); + else + ret = find_next_zero_bit(&tmp, BITS_PER_LONG, + ebit); + if (ret < BITS_PER_LONG) + return ret - 2 + IDA_BITMAP_BITS * index; What I'm saying is that find_next_zero_bit() will not be called if you do "if (ebit >= BITS_PER_LONG) continue;" before calling find_next_zero_bit(). When scanning "0000000000000000000000000000000000000000000000000000000000000001", "bit < BITS_PER_LONG - 2" case finds "0" in this word but "bit >= BITS_PER_LONG - 2" case finds "0" in next word or segment. I can't understand why this is correct behavior. It is too much puzzling.
OK, I'll post out a version without the exceptional path. Best, Wei
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