Re: [PATCH v5 09/11] PCI: liveupdate: Freeze preservation status during shutdown

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] Preservation rollback fails if the device is concurrently frozen, breaking bridge hierarchy invariants.
- [Low] Syntax error in the !CONFIG_PCI_LIVEUPDATE stub for pci_liveupdate_freeze().
--

commit f49768e50767ced554fd83ab7e5016423c3d87a2
Author: David Matlack <dmatlack@google.com>

PCI: liveupdate: Freeze preservation status during shutdown

Freeze a device's outgoing preservation status (preserved or not preserved)
during shutdown. This enables the PCI core and drivers to safely make
decisions based on the device's preservation status during shutdown.

> diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c
> index 6ab03bd548b37..825166a579130 100644
> --- a/drivers/pci/liveupdate.c
> +++ b/drivers/pci/liveupdate.c
> @@ -334,6 +334,11 @@ static int pci_liveupdate_unpreserve_device(struct pci_ser *ser, struct pci_dev
>  
>  	guard(write_lock)(&dev->liveupdate.lock);
>  
> +	if (dev->liveupdate.frozen) {
> +		pci_WARN(dev, 1, "Cannot unpreserve device after it is frozen!\n");
> +		return -EINVAL;
> +	}

During preservation rollback, can this check leave a child device preserved
while its parent is not?

If pci_liveupdate_preserve_path() successfully preserves a child device,
but fails to preserve the parent bridge, it attempts to roll back by calling
pci_liveupdate_unpreserve_device() on the child.

If a concurrent system shutdown calls pci_liveupdate_freeze() on the child
device before this rollback occurs, this check will return -EINVAL and
fail the rollback.

Does this result in a broken topology being passed to the incoming kernel?

[ ... ]

> diff --git a/drivers/pci/liveupdate.h b/drivers/pci/liveupdate.h
> index fd7693c7ddd21..30deaa673efed 100644
> --- a/drivers/pci/liveupdate.h
> +++ b/drivers/pci/liveupdate.h
[ ... ]
> @@ -26,6 +27,10 @@ static inline void pci_liveupdate_cleanup_device(struct pci_dev *dev)
>  {
>  }
>  
> +static inline void pci_liveupdate_freeze(struct pci_dev *dev);
> +{
> +}

Does this stray semicolon after the function signature cause a compilation
error for kernels built without CONFIG_PCI_LIVEUPDATE?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260512184846.119396-1-dmatlack@google.com?part=9