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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