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authorJon Derrick <jonathan.derrick@intel.com>2015-05-27 12:26:23 -0600
committerJens Axboe <axboe@fb.com>2015-06-05 10:33:34 -0600
commit36a7e993eedb2c3f11de3b686b351f75e1edbbb5 (patch)
treef073262e2a058db7a77d4490d422711e8e3c6e46
parent4cc06521ee1f153e0d292413a5bff7bbbdee92d0 (diff)
NVMe: Memory barrier before queue_count is incremented
Protects against reordering and/or preempting which would allow the kthread to access the queue descriptor before it is set up Signed-off-by: Jon Derrick <jonathan.derrick@intel.com> Acked-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
-rw-r--r--drivers/block/nvme-core.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index 9682e29b4171..cae7cac6cc43 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -1453,9 +1453,12 @@ static struct nvme_queue *nvme_alloc_queue(struct nvme_dev *dev, int qid,
nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
nvmeq->q_depth = depth;
nvmeq->qid = qid;
- dev->queue_count++;
dev->queues[qid] = nvmeq;
+ /* make sure queue descriptor is set before queue count, for kthread */
+ mb();
+ dev->queue_count++;
+
return nvmeq;
free_cqdma: