[PATCH] NVMe: Memory barrier before queue_count is incremented

[jonathan.derrick@intel.com (Jon Derrick)]

Ping?

On Wed, May 27, 2015@12:26:23PM -0600, Jon Derrick wrote:
> 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 at intel.com>
> ---
>  drivers/block/nvme-core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
> index c42bc53..2b0c817 100644
> --- a/drivers/block/nvme-core.c
> +++ b/drivers/block/nvme-core.c
> @@ -1463,9 +1463,12 @@ 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:
> -- 
> 2.1.4
>