diff options
Diffstat (limited to 'util/bitmap.c')
| -rw-r--r-- | util/bitmap.c | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/util/bitmap.c b/util/bitmap.c index 9c6bb526f6..300a68e38c 100644 --- a/util/bitmap.c +++ b/util/bitmap.c @@ -11,6 +11,7 @@ #include "qemu/bitops.h" #include "qemu/bitmap.h" +#include "qemu/atomic.h" /* * bitmaps provide an array of bits, implemented using an an @@ -177,6 +178,43 @@ void bitmap_set(unsigned long *map, long start, long nr) } } +void bitmap_set_atomic(unsigned long *map, long start, long nr) +{ + unsigned long *p = map + BIT_WORD(start); + const long size = start + nr; + int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG); + unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start); + + /* First word */ + if (nr - bits_to_set > 0) { + atomic_or(p, mask_to_set); + nr -= bits_to_set; + bits_to_set = BITS_PER_LONG; + mask_to_set = ~0UL; + p++; + } + + /* Full words */ + if (bits_to_set == BITS_PER_LONG) { + while (nr >= BITS_PER_LONG) { + *p = ~0UL; + nr -= BITS_PER_LONG; + p++; + } + } + + /* Last word */ + if (nr) { + mask_to_set &= BITMAP_LAST_WORD_MASK(size); + atomic_or(p, mask_to_set); + } else { + /* If we avoided the full barrier in atomic_or(), issue a + * barrier to account for the assignments in the while loop. + */ + smp_mb(); + } +} + void bitmap_clear(unsigned long *map, long start, long nr) { unsigned long *p = map + BIT_WORD(start); @@ -197,6 +235,51 @@ void bitmap_clear(unsigned long *map, long start, long nr) } } +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; +} + #define ALIGN_MASK(x,mask) (((x)+(mask))&~(mask)) /** |