[PATCH 1/1] nvme: don't ignore tagset allocation failures

[Sagi Grimberg]

> the nvme_dev_add() function silently ignores failures.
> In case blk_mq_alloc_tag_set fails, we hit NULL deref while
> calling blk_mq_init_queue during nvme_alloc_ns with tagset == NULL.
> Instead, we'll not issue the scan_work in case tagset allocation
> failed and leave the ctrl functional.
>
> Signed-off-by: Max Gurtovoy <maxg at mellanox.com>
> Reviewed-by: Keith Busch <keith.busch at intel.com>
> ---
>  drivers/nvme/host/core.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 9b3b57f..493722a 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -2115,9 +2115,9 @@ void nvme_queue_scan(struct nvme_ctrl *ctrl)
>  {
>  	/*
>  	 * Do not queue new scan work when a controller is reset during
> -	 * removal.
> +	 * removal or if the tagset doesn't exist.
>  	 */
> -	if (ctrl->state == NVME_CTRL_LIVE)
> +	if (ctrl->state == NVME_CTRL_LIVE && ctrl->tagset)
>  		schedule_work(&ctrl->scan_work);

This looks wrong...

Why is the controller LIVE without a tagset allocated?
I think you should handle it in the pci driver.