Make dirty iter resistant to resetting bits in corresponding HBitmap.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
Reviewed-by: Max Reitz <mre...@redhat.com>
Reviewed-by: John Snow <js...@redhat.com>
---
include/qemu/hbitmap.h | 26 ++++----------------------
util/hbitmap.c | 23 ++++++++++++++++++++++-
2 files changed, 26 insertions(+), 23 deletions(-)
diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index 9239fe515e..6b04391266 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -256,10 +256,9 @@ void hbitmap_free(HBitmap *hb);
* the lowest-numbered bit that is set in @hb, starting at @first.
*
* Concurrent setting of bits is acceptable, and will at worst cause the
- * iteration to miss some of those bits. Resetting bits before the current
- * position of the iterator is also okay. However, concurrent resetting of
- * bits can lead to unexpected behavior if the iterator has not yet reached
- * those bits.
+ * iteration to miss some of those bits.
+ *
+ * The concurrent resetting of bits is OK.
*/
void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first);
@@ -298,24 +297,7 @@ void hbitmap_free_meta(HBitmap *hb);
* Return the next bit that is set in @hbi's associated HBitmap,
* or -1 if all remaining bits are zero.
*/
-static inline int64_t hbitmap_iter_next(HBitmapIter *hbi)
-{
- unsigned long cur = hbi->cur[HBITMAP_LEVELS - 1];
- int64_t item;
-
- if (cur == 0) {
- cur = hbitmap_iter_skip_words(hbi);
- if (cur == 0) {
- return -1;
- }
- }
-
- /* The next call will resume work from the next bit. */
- hbi->cur[HBITMAP_LEVELS - 1] = cur & (cur - 1);
- item = ((uint64_t)hbi->pos << BITS_PER_LEVEL) + ctzl(cur);
-
- return item << hbi->granularity;
-}
+int64_t hbitmap_iter_next(HBitmapIter *hbi);
/**
* hbitmap_iter_next_word:
diff --git a/util/hbitmap.c b/util/hbitmap.c
index 35088e19c4..0b38817505 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -106,8 +106,9 @@ unsigned long hbitmap_iter_skip_words(HBitmapIter *hbi)
unsigned long cur;
do {
- cur = hbi->cur[--i];
+ i--;
pos >>= BITS_PER_LEVEL;
+ cur = hbi->cur[i] & hb->levels[i][pos];
} while (cur == 0);
/* Check for end of iteration. We always use fewer than BITS_PER_LONG
@@ -139,6 +140,26 @@ unsigned long hbitmap_iter_skip_words(HBitmapIter *hbi)
return cur;
}
+int64_t hbitmap_iter_next(HBitmapIter *hbi)
+{
+ unsigned long cur = hbi->cur[HBITMAP_LEVELS - 1] &
+ hbi->hb->levels[HBITMAP_LEVELS - 1][hbi->pos];
+ int64_t item;
+
+ if (cur == 0) {
+ cur = hbitmap_iter_skip_words(hbi);
+ if (cur == 0) {
+ return -1;
+ }
+ }
+
+ /* The next call will resume work from the next bit. */
+ hbi->cur[HBITMAP_LEVELS - 1] = cur & (cur - 1);
+ item = ((uint64_t)hbi->pos << BITS_PER_LEVEL) + ctzl(cur);
+
+ return item << hbi->granularity;
+}
+
void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first)
{
unsigned i, bit;
--
2.11.1
