diff options
Diffstat (limited to 'block/ll_rw_blk.c')
-rw-r--r-- | block/ll_rw_blk.c | 20 |
1 files changed, 9 insertions, 11 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index d8616e6ebd92..a8a181072bf8 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c | |||
@@ -1057,18 +1057,16 @@ void blk_queue_end_tag(struct request_queue *q, struct request *rq) | |||
1057 | 1057 | ||
1058 | bqt->tag_index[tag] = NULL; | 1058 | bqt->tag_index[tag] = NULL; |
1059 | 1059 | ||
1060 | /* | 1060 | if (unlikely(!test_bit(tag, bqt->tag_map))) { |
1061 | * We use test_and_clear_bit's memory ordering properties here. | ||
1062 | * The tag_map bit acts as a lock for tag_index[bit], so we need | ||
1063 | * a barrer before clearing the bit (precisely: release semantics). | ||
1064 | * Could use clear_bit_unlock when it is merged. | ||
1065 | */ | ||
1066 | if (unlikely(!test_and_clear_bit(tag, bqt->tag_map))) { | ||
1067 | printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n", | 1061 | printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n", |
1068 | __FUNCTION__, tag); | 1062 | __FUNCTION__, tag); |
1069 | return; | 1063 | return; |
1070 | } | 1064 | } |
1071 | 1065 | /* | |
1066 | * The tag_map bit acts as a lock for tag_index[bit], so we need | ||
1067 | * unlock memory barrier semantics. | ||
1068 | */ | ||
1069 | clear_bit_unlock(tag, bqt->tag_map); | ||
1072 | bqt->busy--; | 1070 | bqt->busy--; |
1073 | } | 1071 | } |
1074 | 1072 | ||
@@ -1114,10 +1112,10 @@ int blk_queue_start_tag(struct request_queue *q, struct request *rq) | |||
1114 | if (tag >= bqt->max_depth) | 1112 | if (tag >= bqt->max_depth) |
1115 | return 1; | 1113 | return 1; |
1116 | 1114 | ||
1117 | } while (test_and_set_bit(tag, bqt->tag_map)); | 1115 | } while (test_and_set_bit_lock(tag, bqt->tag_map)); |
1118 | /* | 1116 | /* |
1119 | * We rely on test_and_set_bit providing lock memory ordering semantics | 1117 | * We need lock ordering semantics given by test_and_set_bit_lock. |
1120 | * (could use test_and_set_bit_lock when it is merged). | 1118 | * See blk_queue_end_tag for details. |
1121 | */ | 1119 | */ |
1122 | 1120 | ||
1123 | rq->cmd_flags |= REQ_QUEUED; | 1121 | rq->cmd_flags |= REQ_QUEUED; |