[PATCH v8 04/12] PCI: liveupdate: Document driver binding responsibilities

[Bjorn Helgaas]

On Tue, Jul 28, 2026 at 10:09:58PM +0000, David Matlack wrote:
> Document how driver binding works during a Live Update and what the PCI
> core expects of drivers and users. Note that this is only a description
> of the current division of responsibilities. These can change in the
> future if we decide.
> 
> Reviewed-by: Pasha Tatashin <pasha.tatashin at soleen.com>
> Reviewed-by: Pranjal Shrivastava <praan at google.com>
> Reviewed-by: Samiullah Khawaja <skhawaja at google.com>
> Signed-off-by: David Matlack <dmatlack at google.com>
> ---
>  drivers/pci/liveupdate.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c
> index 5ce5f8b36902..0f7a018ddc66 100644
> --- a/drivers/pci/liveupdate.c
> +++ b/drivers/pci/liveupdate.c
> @@ -71,6 +71,22 @@
>   *
>   *  * The device cannot be a Virtual Function (VF).
>   *  * The device cannot be behind a PCI-to-PCI bridge.
> + *
> + * Driver Binding
> + * ==============
> + *
> + * In the outgoing kernel, it is the driver's responsibility to ensure that it
> + * does not release a device between pci_liveupdate_preserve() and
> + * pci_liveupdate_unpreserve().

Possibly "the driver must ensure" or even "the driver must not
release ..."  Also could apply below.

> + * In the incoming kernel, it is the driver's responsibility to ensure that it
> + * does not release a preserved device between probe() and
> + * pci_liveupdate_finish().
> + *
> + * It is the user's responsibility to ensure that incoming preserved devices are
> + * bound to the correct driver. i.e. The PCI core does not protect against a
> + * device getting preserved by driver A in the outgoing kernel and then getting
> + * bound to driver B in the incoming kernel. This may change in the future.

Same "i.e." nit.

Not sure we need to be reminded that things may change in the future :)