Re: [PATCH 03/10] nvme-multipath: add error handling support for add_disk()

[Keith Busch <kbusch@xxxxxxxxxx>]

On Fri, Aug 27, 2021 at 12:18:02PM -0700, Luis Chamberlain wrote:
> @@ -479,13 +479,17 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, 
> struct nvme_ns_head *head)
>  static void nvme_mpath_set_live(struct nvme_ns *ns)
>  {
>       struct nvme_ns_head *head = ns->head;
> +     int rc;
>  
>       if (!head->disk)
>               return;
>  
> -     if (!test_and_set_bit(NVME_NSHEAD_DISK_LIVE, &head->flags)) {
> -             device_add_disk(&head->subsys->dev, head->disk,
> -                             nvme_ns_id_attr_groups);
> +     if (!test_bit(NVME_NSHEAD_DISK_LIVE, &head->flags)) {

This should still be test_and_set_bit() because it is protecting against
two nvme paths simultaneously calling device_add_disk() on the same
namespace head.

> +             rc = device_add_disk(&head->subsys->dev, head->disk,
> +                                  nvme_ns_id_attr_groups);
> +             if (rc)
> +                     return;
> +             set_bit(NVME_NSHEAD_DISK_LIVE, &head->flags);
>               nvme_add_ns_head_cdev(head);
>       }