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author | David Woodhouse <dwmw2@infradead.org> | 2007-10-13 14:43:54 +0100 |
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committer | David Woodhouse <dwmw2@infradead.org> | 2007-10-13 14:43:54 +0100 |
commit | b160292cc216a50fd0cd386b0bda2cd48352c73b (patch) | |
tree | ef07cf98f91353ee4c9ec1e1ca7a2a5d9d4b538a /block/ll_rw_blk.c | |
parent | b37bde147890c8fea8369a5a4e230dabdea4ebfb (diff) | |
parent | bbf25010f1a6b761914430f5fca081ec8c7accd1 (diff) | |
download | op-kernel-dev-b160292cc216a50fd0cd386b0bda2cd48352c73b.zip op-kernel-dev-b160292cc216a50fd0cd386b0bda2cd48352c73b.tar.gz |
Merge Linux 2.6.23
Diffstat (limited to 'block/ll_rw_blk.c')
-rw-r--r-- | block/ll_rw_blk.c | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index a15845c..ed39313 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -1075,12 +1075,6 @@ void blk_queue_end_tag(struct request_queue *q, struct request *rq) */ return; - if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) { - printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n", - __FUNCTION__, tag); - return; - } - list_del_init(&rq->queuelist); rq->cmd_flags &= ~REQ_QUEUED; rq->tag = -1; @@ -1090,6 +1084,19 @@ void blk_queue_end_tag(struct request_queue *q, struct request *rq) __FUNCTION__, tag); bqt->tag_index[tag] = NULL; + + /* + * We use test_and_clear_bit's memory ordering properties here. + * The tag_map bit acts as a lock for tag_index[bit], so we need + * a barrer before clearing the bit (precisely: release semantics). + * Could use clear_bit_unlock when it is merged. + */ + if (unlikely(!test_and_clear_bit(tag, bqt->tag_map))) { + printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n", + __FUNCTION__, tag); + return; + } + bqt->busy--; } @@ -1136,6 +1143,10 @@ int blk_queue_start_tag(struct request_queue *q, struct request *rq) return 1; } while (test_and_set_bit(tag, bqt->tag_map)); + /* + * We rely on test_and_set_bit providing lock memory ordering semantics + * (could use test_and_set_bit_lock when it is merged). + */ rq->cmd_flags |= REQ_QUEUED; rq->tag = tag; |