Re: [PATCH v6 01/12] PCI: liveupdate: Set up FLB handler for the PCI core

[Mike Rapoport <rppt@kernel.org>]

On Fri, May 22, 2026 at 02:37:28PM -0700, David Matlack wrote:
> On Fri, May 22, 2026 at 1:44 PM <sashiko-bot@kernel.org> wrote:
> >
> > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> > - [Medium] Missing `kho_is_enabled()` check before calling KHO preservation APIs in PCI Live Update FLB operations.
> > --
> >
> > commit b0cb2fb154fba1aa85d63570fe0186e243353fb7
> > Author: David Matlack <dmatlack@google.com>
> >
> > PCI: liveupdate: Set up FLB handler for the PCI core
> >
> > This commit sets up a File-Lifecycle-Bound (FLB) handler for the PCI core
> > to participate in the preservation of PCI devices across Live Update. It
> > allocates and preserves a pci_ser structure using KHO when the first PCI
> > device file is preserved.
> >
> > > diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c
> > > new file mode 100644
> > > --- /dev/null
> > > +++ b/drivers/pci/liveupdate.c
> >
> > [ ... ]
> >
> > > +static int pci_flb_preserve(struct liveupdate_flb_op_args *args)
> > > +{
> > > +     struct pci_dev *dev = NULL;
> > > +     u32 max_nr_devices = 0;
> > > +     struct pci_ser *ser;
> > > +     unsigned long size;
> > > +
> > > +     /*
> > > +      * Allocate enough space to preserve all devices that are currently
> > > +      * present on the system. Extra padding can be added to this in the
> > > +      * future to increase the chances that there is enough room to preserve
> > > +      * devices that are not yet present on the system (e.g. VFs, hot-plugged
> > > +      * devices).
> > > +      */
> > > +     for_each_pci_dev(dev)
> > > +             max_nr_devices++;
> > > +
> > > +     size = struct_size_t(struct pci_ser, devices, max_nr_devices);
> > > +
> > > +     ser = kho_alloc_preserve(size);
> >
> > [Severity: Medium]
> > Should this code verify kho_is_enabled() before calling kho_alloc_preserve()?
> >
> > The commit message states:
> > "Note: There is no reason to check for kho_is_enabled() since it can be
> > assumed to return true. If KHO was not enabled then Live Update would
> > not be enabled and these routines would never run."
> >
> > Does this assumption conflict with the Kexec Handover subsystem guidelines?
> >
> > The guidelines mandate that all callers of serialization APIs must explicitly
> > gate their usage with kho_is_enabled().
> >
> > Calling preservation APIs like kho_alloc_preserve() without the check can
> > silently add tracking state that will never be used if the subsystem is
> > unexpectedly inactive.
> 
> Sashiko keeps leaving this comment. It seems like a false positive to
> me. KHO maintainers, perhaps the KHO documentation needs adjustment?

TBH, I don't remember such guidelines, but patches are welcome ;-)

-- 
Sincerely yours,
Mike.