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

- From: Luis Chamberlain \<mcgrof@kernel.org\>
- Date: 2021-08-30 21:09:10 
- List: linux-bcache
- Page: https://ratatoskr.run/linux-bcache/2021/08/1492641
- Thread: https://ratatoskr.run/xen-devel/2021/08/1490846/t.md

```text
On Fri, Aug 27, 2021 at 01:29:32PM -0700, Keith Busch wrote:
> 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.

Interesting, I'll add a comment as well, as this was not clear with the drive
by effort.

  Luis
```