diff options
Diffstat (limited to 'lib/sbitmap.c')
| -rw-r--r-- | lib/sbitmap.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/lib/sbitmap.c b/lib/sbitmap.c index 5b382c1244ed..4a7fc4915dfc 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -435,7 +435,7 @@ static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq, * to ensure that the batch size is updated before the wait * counts. */ - smp_mb__before_atomic(); + smp_mb(); for (i = 0; i < SBQ_WAIT_QUEUES; i++) atomic_set(&sbq->ws[i].wait_cnt, 1); } @@ -591,6 +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); /* |