PCI: Split out next_ari_fn() from next_fn()

In commit b1bd58e4 ("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.

Link: https://lore.kernel.org/r/20220628143100.3228092-3-schnelle@linux.ibm.comSigned-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>

drivers/pci/probe.c

@@ -2579,26 +2579,31 @@ 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;
 
-		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 */
+	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);
+	if (!pos)
+		return -ENODEV;
 
-		return next_fn;
-	}
+	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;
+}
+
+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;