bool bitmap_test_and_clear_atomic(unsigned long *map, long start, long nr) { unsigned long *p = map + BIT_WORD(start); const long size = start + nr; int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG); unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start); unsigned long dirty = 0; unsigned long old_bits; /* First word */ if (nr - bits_to_clear > 0) { old_bits = atomic_fetch_and(p, ~mask_to_clear); dirty |= old_bits & mask_to_clear; nr -= bits_to_clear; bits_to_clear = BITS_PER_LONG; mask_to_clear = ~0UL; p++; } /* Full words */ if (bits_to_clear == BITS_PER_LONG) { while (nr >= BITS_PER_LONG) { if (*p) { old_bits = atomic_xchg(p, 0); dirty |= old_bits; } nr -= BITS_PER_LONG; p++; } } /* Last word */ if (nr) { mask_to_clear &= BITMAP_LAST_WORD_MASK(size); old_bits = atomic_fetch_and(p, ~mask_to_clear); dirty |= old_bits & mask_to_clear; } else { if (!dirty) { smp_mb(); } } return dirty != 0; }