diff options
| -rw-r--r-- | block/ll_rw_blk.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index f757ed41321..83425fb3c8d 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -1171,11 +1171,16 @@ int blk_queue_start_tag(request_queue_t *q, struct request *rq) BUG(); } - tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth); - if (tag >= bqt->max_depth) - return 1; + /* + * Protect against shared tag maps, as we may not have exclusive + * access to the tag map. + */ + do { + tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth); + if (tag >= bqt->max_depth) + return 1; - __set_bit(tag, bqt->tag_map); + } while (test_and_set_bit(tag, bqt->tag_map)); rq->cmd_flags |= REQ_QUEUED; rq->tag = tag; |