Re: [PATCH v4 01/11] PCI: liveupdate: Set up FLB handler for the PCI core

Vipin Sharma
2026-04-28T19:45:59Z

On Thu, Apr 23, 2026 at 09:23:05PM +0000, David Matlack wrote:
> + pr_debug("Preserving struct pci_ser with room for %u devices\n",
> + max_nr_devices);
> +
> + ser = kho_alloc_preserve(size);
> + if (IS_ERR(ser))
> + return PTR_ERR(ser);

Should there be a similar pr_debug() in case of failure to denote that above
"Preserving ..." message didn't finish, or, maybe just print one
pr_debug() after the error check above?

> +/**
> + * struct pci_dev_ser - Serialized state about a single PCI device.
> + *
> + * @domain: The device's PCI domain number (segment).
> + * @bdf: The device's PCI bus, device, and function number.
> + * @reserved: Reserved (to naturally align struct pci_dev_ser).
> + */
> +struct pci_dev_ser {
> + u32 domain;
> + u16 bdf;
> + u16 reserved;

Should this be renamed to 'u8 __padding[2];' instead? This will allow to
just change the array length based on the need (0, 1, 2, 3).

> +} __packed;
> +
> +/**
> + * struct pci_ser - PCI Subsystem Live Update State
> + *
> + * This struct tracks state about all devices that are being preserved across
> + * a Live Update for the next kernel.
> + *
> + * @max_nr_devices: The length of the devices[] flexible array.
> + * @nr_devices: The number of devices that were preserved.
> + * @devices: Flexible array of pci_dev_ser structs for each device.
> + */
> +struct pci_ser {
> + u32 max_nr_devices;
> + u32 nr_devices;
> + struct pci_dev_ser devices[];
> +} __packed;
> +
> +/* Ensure all elements of devices[] are naturally aligned. */
> +static_assert(offsetof(struct pci_ser, devices) % sizeof(unsigned long) == 0);
> +static_assert(sizeof(struct pci_dev_ser) % sizeof(unsigned long) == 0);

Nit: Maybe move this assert to be near to the definition of this struct,
easier to find it when editing the struct vs finding it later during
build.