hv_netvsc: fix vf serial matching with pci slot info

The VF device's serial number is saved as a string in PCI slot's
kobj name, not the slot->number. This patch corrects the netvsc
driver, so the VF device can be successfully paired with synthetic
NIC.

Fixes: 00d7ddba ("hv_netvsc: pair VF based on serial number")
Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hyperv/netvsc_drv.c

@@ -2030,14 +2030,15 @@ static void netvsc_vf_setup(struct work_struct *w)
 	rtnl_unlock();
 }
 
-/* Find netvsc by VMBus serial number.
- * The PCI hyperv controller records the serial number as the slot.
+/* Find netvsc by VF serial number.
+ * The PCI hyperv controller records the serial number as the slot kobj name.
  */
 static struct net_device *get_netvsc_byslot(const struct net_device *vf_netdev)
 {
 	struct device *parent = vf_netdev->dev.parent;
 	struct net_device_context *ndev_ctx;
 	struct pci_dev *pdev;
+	u32 serial;
 
 	if (!parent || !dev_is_pci(parent))
 		return NULL; /* not a PCI device */
@@ -2048,16 +2049,22 @@ static struct net_device *get_netvsc_byslot(const struct net_device *vf_netdev)
 		return NULL;
 	}
 
+	if (kstrtou32(pci_slot_name(pdev->slot), 10, &serial)) {
+		netdev_notice(vf_netdev, "Invalid vf serial:%s\n",
+			      pci_slot_name(pdev->slot));
+		return NULL;
+	}
+
 	list_for_each_entry(ndev_ctx, &netvsc_dev_list, list) {
 		if (!ndev_ctx->vf_alloc)
 			continue;
 
-		if (ndev_ctx->vf_serial == pdev->slot->number)
+		if (ndev_ctx->vf_serial == serial)
 			return hv_get_drvdata(ndev_ctx->device_ctx);
 	}
 
 	netdev_notice(vf_netdev,
-		      "no netdev found for slot %u\n", pdev->slot->number);
+		      "no netdev found for vf serial:%u\n", serial);
 	return NULL;
 }