1 files changed, 18 insertions, 26 deletions

diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 267aa7709416..d693d9213ceb 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -12,33 +12,24 @@
 /*
  * See if we have deferred clears that we can batch move
  */
-static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index)
+static inline bool sbitmap_deferred_clear(struct sbitmap_word *map)
 {
-	unsigned long mask, val;
-	bool ret = false;
-	unsigned long flags;
+	unsigned long mask;
 
-	spin_lock_irqsave(&sb->map[index].swap_lock, flags);
-
-	if (!sb->map[index].cleared)
-		goto out_unlock;
+	if (!READ_ONCE(map->cleared))
+		return false;
 
 	/*
 	 * First get a stable cleared mask, setting the old mask to 0.
 	 */
-	mask = xchg(&sb->map[index].cleared, 0);
+	mask = xchg(&map->cleared, 0);
 
 	/*
 	 * Now clear the masked bits in our free word
 	 */
-	do {
-		val = sb->map[index].word;
-	} while (cmpxchg(&sb->map[index].word, val, val & ~mask) != val);
-
-	ret = true;
-out_unlock:
-	spin_unlock_irqrestore(&sb->map[index].swap_lock, flags);
-	return ret;
+	atomic_long_andnot(mask, (atomic_long_t *)&map->word);
+	BUILD_BUG_ON(sizeof(atomic_long_t) != sizeof(map->word));
+	return true;
 }
 
 int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
@@ -80,7 +71,6 @@ int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
 	for (i = 0; i < sb->map_nr; i++) {
 		sb->map[i].depth = min(depth, bits_per_word);
 		depth -= sb->map[i].depth;
-		spin_lock_init(&sb->map[i].swap_lock);
 	}
 	return 0;
 }
@@ -92,7 +82,7 @@ void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
 	unsigned int i;
 
 	for (i = 0; i < sb->map_nr; i++)
-		sbitmap_deferred_clear(sb, i);
+		sbitmap_deferred_clear(&sb->map[i]);
 
 	sb->depth = depth;
 	sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
@@ -107,9 +97,11 @@ EXPORT_SYMBOL_GPL(sbitmap_resize);
 static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
 			      unsigned int hint, bool wrap)
 {
-	unsigned int orig_hint = hint;
 	int nr;
 
+	/* don't wrap if starting from 0 */
+	wrap = wrap && hint;
+
 	while (1) {
 		nr = find_next_zero_bit(word, depth, hint);
 		if (unlikely(nr >= depth)) {
@@ -118,8 +110,8 @@ static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
 			 * offset to 0 in a failure case, so start from 0 to
 			 * exhaust the map.
 			 */
-			if (orig_hint && hint && wrap) {
-				hint = orig_hint = 0;
+			if (hint && wrap) {
+				hint = 0;
 				continue;
 			}
 			return -1;
@@ -139,15 +131,15 @@ static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
 static int sbitmap_find_bit_in_index(struct sbitmap *sb, int index,
 				     unsigned int alloc_hint, bool round_robin)
 {
+	struct sbitmap_word *map = &sb->map[index];
 	int nr;
 
 	do {
-		nr = __sbitmap_get_word(&sb->map[index].word,
-					sb->map[index].depth, alloc_hint,
+		nr = __sbitmap_get_word(&map->word, map->depth, alloc_hint,
 					!round_robin);
 		if (nr != -1)
 			break;
-		if (!sbitmap_deferred_clear(sb, index))
+		if (!sbitmap_deferred_clear(map))
 			break;
 	} while (1);
 
@@ -207,7 +199,7 @@ again:
 			break;
 		}
 
-		if (sbitmap_deferred_clear(sb, index))
+		if (sbitmap_deferred_clear(&sb->map[index]))
 			goto again;
 
 		/* Jump to next index. */