Re: [PATCHv3 2/5] pci: Add is_removed state

[Keith Busch <keith.busch@intel.com>]

On Fri, Oct 21, 2016 at 06:20:10PM +0200, Lukas Wunner wrote:
> I've found that the following simple change on top of your series is
> already sufficient to make hot-removal of the Apple Gigabit Ethernet
> adapter "just work" (no more soft lockups, which is a giant improvement):
> 
> 
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 5c43012..cc8b234 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -406,7 +406,7 @@ struct pci_dev *pci_alloc_dev(struct pci_bus *bus);
>  
>  static inline int pci_channel_offline(struct pci_dev *pdev)
>  {
> -	return (pdev->error_state != pci_channel_io_normal);
> +	return pdev->error_state != pci_channel_io_normal || pdev->is_removed;
>  }
>  
>  struct pci_host_bridge {
> 
> 
> This got me thinking:  We've got three pci_channel_state values defined
> in include/linux/pci.h, "normal", "frozen" and "perm_failure".  Instead
> of adding a new "is_removed" bit to struct pci_dev, would it perhaps
> make more sense to just add a new type of pci_channel_state for removed
> devices?  Then the above change to pci_channel_offline() wouldn't even
> be necessary.  The pciehp and dpc drivers would just change the channel
> status to "removed" and all the drivers already querying it with
> pci_channel_offline() would pick up the change automatically.
> 
> Thoughts?

I'd be happy if we can reuse that, but concerned about overloading
error_state's intended purpose for AER. The conditions under which an
'is_removed' may be set can also create AER events, and the aer driver
overrides the error_state.