Because of spinlocks and atomics sbitmap_deferred_clear() have to reload &sb->map[index] on each access even though the map address won't change. Hint it by explicitly caching it in a variable.
Signed-off-by: Pavel Begunkov <[email protected]> --- lib/sbitmap.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/lib/sbitmap.c b/lib/sbitmap.c index 267aa7709416..49afb34e8340 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -14,30 +14,31 @@ */ static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index) { + struct sbitmap_word *map = &sb->map[index]; unsigned long mask, val; bool ret = false; unsigned long flags; - spin_lock_irqsave(&sb->map[index].swap_lock, flags); + spin_lock_irqsave(&map->swap_lock, flags); - if (!sb->map[index].cleared) + if (!map->cleared) goto out_unlock; /* * 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); + val = map->word; + } while (cmpxchg(&map->word, val, val & ~mask) != val); ret = true; out_unlock: - spin_unlock_irqrestore(&sb->map[index].swap_lock, flags); + spin_unlock_irqrestore(&map->swap_lock, flags); return ret; } -- 2.24.0
