[PATCH v2 3/5] sbitmap: rewrite sbitmap_find_bit_in_index to reduce repeat code

From: Kemeng Shi
Date: Thu Dec 15 2022 - 07:37:42 EST


Rewrite sbitmap_find_bit_in_index as following:
1. Rename sbitmap_find_bit_in_index to sbitmap_find_bit_in_word
2. Accept "struct sbitmap_word *" directly instead of accepting
"struct sbitmap *" and "int index" to get "struct sbitmap_word *".
3. Accept depth/shallow_depth and wrap for __sbitmap_get_word from caller
to support need of both __sbitmap_get_shallow and __sbitmap_get.

With helper function sbitmap_find_bit_in_word, we can remove repeat
code in __sbitmap_get_shallow to find bit considring deferred clear.

Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
---
lib/sbitmap.c | 29 ++++++++++++++---------------
1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 11e75f4040fb..3f7e276a427d 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -167,15 +167,16 @@ 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)
+static int sbitmap_find_bit_in_word(struct sbitmap_word *map,
+ unsigned int depth,
+ unsigned int alloc_hint,
+ bool wrap)
{
- struct sbitmap_word *map = &sb->map[index];
int nr;

do {
- nr = __sbitmap_get_word(&map->word, __map_depth(sb, index),
- alloc_hint, !sb->round_robin);
+ nr = __sbitmap_get_word(&map->word, depth,
+ alloc_hint, wrap);
if (nr != -1)
break;
if (!sbitmap_deferred_clear(map))
@@ -203,7 +204,8 @@ static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint)
alloc_hint = 0;

for (i = 0; i < sb->map_nr; i++) {
- nr = sbitmap_find_bit_in_index(sb, index, alloc_hint);
+ nr = sbitmap_find_bit_in_word(&sb->map[index], __map_depth(sb, index),
+ alloc_hint, !sb->round_robin);
if (nr != -1) {
nr += index << sb->shift;
break;
@@ -246,20 +248,17 @@ static int __sbitmap_get_shallow(struct sbitmap *sb,
alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);

for (i = 0; i < sb->map_nr; i++) {
-again:
- nr = __sbitmap_get_word(&sb->map[index].word,
- min_t(unsigned int,
- __map_depth(sb, index),
- shallow_depth),
- alloc_hint, true);
+ nr = sbitmap_find_bit_in_word(&sb->map[index],
+ min_t(unsigned int,
+ __map_depth(sb, index),
+ shallow_depth),
+ alloc_hint, true);
+
if (nr != -1) {
nr += index << sb->shift;
break;
}

- if (sbitmap_deferred_clear(&sb->map[index]))
- goto again;
-
/* Jump to next index. */
alloc_hint = 0;
if (++index >= sb->map_nr)
--
2.30.0