Re: [PATCH] xen/pcifront: move xenstore config scanning into sub-function

[Juergen Gross]

On 06.10.22 15:29, Jason Andryuk wrote:
> On Thu, Oct 6, 2022 at 5:29 AM Juergen Gross <jgross@xxxxxxxx> wrote:
> > pcifront_try_connect() and pcifront_attach_devices() share a large
> > chunk of duplicated code for reading the config information from
> > Xenstore, which only differs regarding a function call.
> >
> > Put that code into a new sub-function. While at it fix the error
> > reporting in case the root-xx node had the wrong format.
> >
> > As the return value of pcifront_try_connect() and
> > pcifront_attach_devices() are not used anywhere make those functions
> > return void. As an additional bonus this removes the dubious return
> > of -EFAULT in case of an unexpected driver state.
> >
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > ---
> >   drivers/pci/xen-pcifront.c | 133 +++++++++++--------------------------
> >   1 file changed, 40 insertions(+), 93 deletions(-)
> >
> > diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
> > index 689271c4245c..a68e47dcdd7e 100644
> > --- a/drivers/pci/xen-pcifront.c
> > +++ b/drivers/pci/xen-pcifront.c
> > @@ -819,76 +819,79 @@ static int pcifront_publish_info(struct pcifront_device *pdev)
>
> >          err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend,
> >                             "root_num", "%d", &num_roots);
> >          if (err == -ENOENT) {
> >                  xenbus_dev_error(pdev->xdev, err,
> >                                   "No PCI Roots found, trying 0000:00");
> > -               err = pcifront_scan_root(pdev, 0, 0);
> > +               if (rescan)
> > +                       err = pcifront_rescan_root(pdev, 0, 0);
> > +               else
> > +                       err = pcifront_scan_root(pdev, 0, 0);
>
> Early in pcifront_rescan_root(), we have:
>
>          b = pci_find_bus(domain, bus);
>          if (!b)
>                  /* If the bus is unknown, create it. */
>                  return pcifront_scan_root(pdev, domain, bus);
>
> pcifront_scan_root() does some allocation, but the later scanning
> matches that of pcifront_rescan_root().  So I think we can just always
> call pcifront_rescan_root() and it should do the right thing.  That
> drops the need for the rescan boolean.

Hmm, with some more pcifront_rescan_root() adaption this will make it
possible to drop even more code (i.e. the CONFIG_PCI_DOMAINS check in
pcifront_rescan_root(), as the one in pcifront_scan_root() would be
enough then).

I'll send out V2 soon.

> Regardless of the above idea:
>
> Reviewed-by: Jason Andryuk <jandryuk@xxxxxxxxx>

Thanks. As I'm about to change the patch, I'll drop the R-b.


Juergen

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