diff options
Diffstat (limited to 'lib/sbitmap.c')
| -rw-r--r-- | lib/sbitmap.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/lib/sbitmap.c b/lib/sbitmap.c index 65c2d06250a6..155fe38756ec 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -26,14 +26,10 @@ static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index) { unsigned long mask, val; - unsigned long __maybe_unused flags; bool ret = false; + unsigned long flags; - /* Silence bogus lockdep warning */ -#if defined(CONFIG_LOCKDEP) - local_irq_save(flags); -#endif - spin_lock(&sb->map[index].swap_lock); + spin_lock_irqsave(&sb->map[index].swap_lock, flags); if (!sb->map[index].cleared) goto out_unlock; @@ -54,10 +50,7 @@ static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index) ret = true; out_unlock: - spin_unlock(&sb->map[index].swap_lock); -#if defined(CONFIG_LOCKDEP) - local_irq_restore(flags); -#endif + spin_unlock_irqrestore(&sb->map[index].swap_lock, flags); return ret; } @@ -598,6 +591,17 @@ EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up); void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr, unsigned int cpu) { + /* + * Once the clear bit is set, the bit may be allocated out. + * + * Orders READ/WRITE on the asssociated instance(such as request + * of blk_mq) by this bit for avoiding race with re-allocation, + * and its pair is the memory barrier implied in __sbitmap_get_word. + * + * One invariant is that the clear bit has to be zero when the bit + * is in use. + */ + smp_mb__before_atomic(); sbitmap_deferred_clear_bit(&sbq->sb, nr); /* |