diff options
| -rw-r--r-- | include/linux/sbitmap.h | 13 | ||||
| -rw-r--r-- | lib/sbitmap.c | 51 |
2 files changed, 64 insertions, 0 deletions
diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h index 2713e689ad66..e30b56023ead 100644 --- a/include/linux/sbitmap.h +++ b/include/linux/sbitmap.h @@ -427,6 +427,19 @@ void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth); int __sbitmap_queue_get(struct sbitmap_queue *sbq); /** + * __sbitmap_queue_get_batch() - Try to allocate a batch of free bits + * @sbq: Bitmap queue to allocate from. + * @nr_tags: number of tags requested + * @offset: offset to add to returned bits + * + * Return: Mask of allocated tags, 0 if none are found. Each tag allocated is + * a bit in the mask returned, and the caller must add @offset to the value to + * get the absolute tag value. + */ +unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags, + unsigned int *offset); + +/** * __sbitmap_queue_get_shallow() - Try to allocate a free bit from a &struct * sbitmap_queue, limiting the depth used from each word, with preemption * already disabled. diff --git a/lib/sbitmap.c b/lib/sbitmap.c index b25db9be938a..f398e0ae548e 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -489,6 +489,57 @@ int __sbitmap_queue_get(struct sbitmap_queue *sbq) } EXPORT_SYMBOL_GPL(__sbitmap_queue_get); +unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags, + unsigned int *offset) +{ + struct sbitmap *sb = &sbq->sb; + unsigned int hint, depth; + unsigned long index, nr; + int i; + + if (unlikely(sb->round_robin)) + return 0; + + depth = READ_ONCE(sb->depth); + hint = update_alloc_hint_before_get(sb, depth); + + index = SB_NR_TO_INDEX(sb, hint); + + for (i = 0; i < sb->map_nr; i++) { + struct sbitmap_word *map = &sb->map[index]; + unsigned long get_mask; + + sbitmap_deferred_clear(map); + if (map->word == (1UL << (map->depth - 1)) - 1) + continue; + + nr = find_first_zero_bit(&map->word, map->depth); + if (nr + nr_tags <= map->depth) { + atomic_long_t *ptr = (atomic_long_t *) &map->word; + int map_tags = min_t(int, nr_tags, map->depth); + unsigned long val, ret; + + get_mask = ((1UL << map_tags) - 1) << nr; + do { + val = READ_ONCE(map->word); + ret = atomic_long_cmpxchg(ptr, val, get_mask | val); + } while (ret != val); + get_mask = (get_mask & ~ret) >> nr; + if (get_mask) { + *offset = nr + (index << sb->shift); + update_alloc_hint_after_get(sb, depth, hint, + *offset + map_tags - 1); + return get_mask; + } + } + /* Jump to next index. */ + if (++index >= sb->map_nr) + index = 0; + } + + return 0; +} + int __sbitmap_queue_get_shallow(struct sbitmap_queue *sbq, unsigned int shallow_depth) { |