This is in preparation for doing something better, which doesn't need
us to maintain two sets of bitmaps.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
include/linux/sbitmap.h | 25 +-----------
lib/sbitmap.c | 88 +++++------------------------------------
2 files changed, 10 insertions(+), 103 deletions(-)
diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h
index e40d019c3d9d..7cdd82e0e0dd 100644
--- a/include/linux/sbitmap.h
+++ b/include/linux/sbitmap.h
@@ -27,16 +27,6 @@ struct sbitmap_word {
* @word: word holding free bits
*/
unsigned long word ____cacheline_aligned_in_smp;
-
- /**
- * @cleared: word holding cleared bits
- */
- unsigned long cleared ____cacheline_aligned_in_smp;
-
- /**
- * @swap_lock: Held while swapping word <-> cleared
- */
- spinlock_t swap_lock;
} ____cacheline_aligned_in_smp;
/**
@@ -251,7 +241,7 @@ static inline void __sbitmap_for_each_set(struct sbitmap *sb,
sb->depth - scanned);
scanned += depth;
- word = sb->map[index].word & ~sb->map[index].cleared;
+ word = sb->map[index].word;
if (!word)
goto next;
@@ -307,19 +297,6 @@ static inline void sbitmap_clear_bit(struct sbitmap *sb, unsigned int bitnr)
clear_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr));
}
-/*
- * This one is special, since it doesn't actually clear the bit, rather it
- * sets the corresponding bit in the ->cleared mask instead. Paired with
- * the caller doing sbitmap_deferred_clear() if a given index is full, which
- * will clear the previously freed entries in the corresponding ->word.
- */
-static inline void sbitmap_deferred_clear_bit(struct sbitmap *sb, unsigned int bitnr)
-{
- unsigned long *addr = &sb->map[SB_NR_TO_INDEX(sb, bitnr)].cleared;
-
- set_bit(SB_NR_TO_BIT(sb, bitnr), addr);
-}
-
static inline void sbitmap_clear_bit_unlock(struct sbitmap *sb,
unsigned int bitnr)
{
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 33feec8989f1..af6d6578809f 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -9,38 +9,6 @@
#include <linux/sbitmap.h>
#include <linux/seq_file.h>
-/*
- * See if we have deferred clears that we can batch move
- */
-static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index)
-{
- unsigned long mask, val;
- bool ret = false;
- unsigned long flags;
-
- spin_lock_irqsave(&sb->map[index].swap_lock, flags);
-
- if (!sb->map[index].cleared)
- goto out_unlock;
-
- /*
- * First get a stable cleared mask, setting the old mask to 0.
- */
- mask = xchg(&sb->map[index].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;
-}
-
int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
gfp_t flags, int node)
{
@@ -80,7 +48,6 @@ 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;
}
@@ -91,9 +58,6 @@ void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
unsigned int bits_per_word = 1U << sb->shift;
unsigned int i;
- for (i = 0; i < sb->map_nr; i++)
- sbitmap_deferred_clear(sb, i);
-
sb->depth = depth;
sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
@@ -136,24 +100,6 @@ static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
return nr;
}
-static int sbitmap_find_bit_in_index(struct sbitmap *sb, int index,
- unsigned int alloc_hint, bool round_robin)
-{
- int nr;
-
- do {
- nr = __sbitmap_get_word(&sb->map[index].word,
- sb->map[index].depth, alloc_hint,
- !round_robin);
- if (nr != -1)
- break;
- if (!sbitmap_deferred_clear(sb, index))
- break;
- } while (1);
-
- return nr;
-}
-
int sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint, bool round_robin)
{
unsigned int i, index;
@@ -172,8 +118,10 @@ int sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint, bool round_robin)
alloc_hint = 0;
for (i = 0; i < sb->map_nr; i++) {
- nr = sbitmap_find_bit_in_index(sb, index, alloc_hint,
- round_robin);
+ nr = __sbitmap_get_word(&sb->map[index].word,
+ sb->map[index].depth, alloc_hint,
+ !round_robin);
+
if (nr != -1) {
nr += index << sb->shift;
break;
@@ -198,7 +146,6 @@ int sbitmap_get_shallow(struct sbitmap *sb, unsigned int alloc_hint,
index = SB_NR_TO_INDEX(sb, alloc_hint);
for (i = 0; i < sb->map_nr; i++) {
-again:
nr = __sbitmap_get_word(&sb->map[index].word,
min(sb->map[index].depth, shallow_depth),
SB_NR_TO_BIT(sb, alloc_hint), true);
@@ -207,9 +154,6 @@ int sbitmap_get_shallow(struct sbitmap *sb, unsigned int alloc_hint,
break;
}
- if (sbitmap_deferred_clear(sb, index))
- goto again;
-
/* Jump to next index. */
index++;
alloc_hint = index << sb->shift;
@@ -229,43 +173,29 @@ bool sbitmap_any_bit_set(const struct sbitmap *sb)
unsigned int i;
for (i = 0; i < sb->map_nr; i++) {
- if (sb->map[i].word & ~sb->map[i].cleared)
+ if (sb->map[i].word)
return true;
}
return false;
}
EXPORT_SYMBOL_GPL(sbitmap_any_bit_set);
-static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)
+static unsigned int sbitmap_weight(const struct sbitmap *sb)
{
unsigned int i, weight = 0;
for (i = 0; i < sb->map_nr; i++) {
const struct sbitmap_word *word = &sb->map[i];
- if (set)
- weight += bitmap_weight(&word->word, word->depth);
- else
- weight += bitmap_weight(&word->cleared, word->depth);
+ weight += bitmap_weight(&word->word, word->depth);
}
return weight;
}
-static unsigned int sbitmap_weight(const struct sbitmap *sb)
-{
- return __sbitmap_weight(sb, true);
-}
-
-static unsigned int sbitmap_cleared(const struct sbitmap *sb)
-{
- return __sbitmap_weight(sb, false);
-}
-
void sbitmap_show(struct sbitmap *sb, struct seq_file *m)
{
seq_printf(m, "depth=%u\n", sb->depth);
- seq_printf(m, "busy=%u\n", sbitmap_weight(sb) - sbitmap_cleared(sb));
- seq_printf(m, "cleared=%u\n", sbitmap_cleared(sb));
+ seq_printf(m, "busy=%u\n", sbitmap_weight(sb));
seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift);
seq_printf(m, "map_nr=%u\n", sb->map_nr);
}
@@ -570,7 +500,7 @@ void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
* is in use.
*/
smp_mb__before_atomic();
- sbitmap_deferred_clear_bit(&sbq->sb, nr);
+ sbitmap_clear_bit_unlock(&sbq->sb, nr);
/*
* Pairs with the memory barrier in set_current_state() to ensure the
--
2.24.1
