Re: [PATCH v6 2/5] PCI: Split out next_ari_fn() from next_fn()

Pierre Morel
2022-06-30T12:40:36Z

On 6/28/22 16:30, Niklas Schnelle wrote:
> In commit b1bd58e448f2 ("PCI: Consolidate "next-function" functions")
> the next_fn() function subsumed the traditional and ARI based next
> function determination. This got rid of some needlessly complex function
> pointer handling but also reduced the separation between these very
> different methods of finding the next function. With the next_fn()
> cleaned up a bit we can re-introduce this separation by moving out the
> ARI handling while sticking with direct function calls.
>
> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> ---
> drivers/pci/probe.c | 30 +++++++++++++++++-------------
> 1 file changed, 17 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index b05d0ed83a24..2c737dce757e 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2579,26 +2579,30 @@ struct pci_dev *pci_scan_single_device(struct pci_bus *bus, int devfn)
> }
> EXPORT_SYMBOL(pci_scan_single_device);
>
> -static int next_fn(struct pci_bus *bus, struct pci_dev *dev, int fn)
> +static int next_ari_fn(struct pci_bus *bus, struct pci_dev *dev, int fn)
> {
> int pos;
> u16 cap = 0;
> unsigned int next_fn;
>
> - if (pci_ari_enabled(bus)) {
> - if (!dev)
> - return -ENODEV;
> - pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);
> - if (!pos)
> - return -ENODEV;
> + if (!dev)
> + return -ENODEV;
> + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);
> + if (!pos)
> + return -ENODEV;
> +
> + pci_read_config_word(dev, pos + PCI_ARI_CAP, &cap);
> + next_fn = PCI_ARI_CAP_NFN(cap);
> + if (next_fn <= fn)
> + return -ENODEV; /* protect against malformed list */
>
> - pci_read_config_word(dev, pos + PCI_ARI_CAP, &cap);
> - next_fn = PCI_ARI_CAP_NFN(cap);
> - if (next_fn <= fn)
> - return -ENODEV; /* protect against malformed list */
> + return next_fn;
> +}
>
> - return next_fn;
> - }
> +static int next_fn(struct pci_bus *bus, struct pci_dev *dev, int fn)
> +{
> + if (pci_ari_enabled(bus))
> + return next_ari_fn(bus, dev, fn);
>
> if (fn >= 7)
> return -ENODEV;
>

Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>

--
Pierre Morel
IBM Lab Boeblingen