idpf: check error for register_netdev() on init

Current init logic ignores the error code from register_netdev(),
which will cause WARN_ON() on attempt to unregister it, if there was one,
and there is no info for the user that the creation of the netdev failed.

WARNING: CPU: 89 PID: 6902 at net/core/dev.c:11512 unregister_netdevice_many_notify+0x211/0x1a10
...
[ 3707.563641]  unregister_netdev+0x1c/0x30
[ 3707.563656]  idpf_vport_dealloc+0x5cf/0xce0 [idpf]
[ 3707.563684]  idpf_deinit_task+0xef/0x160 [idpf]
[ 3707.563712]  idpf_vc_core_deinit+0x84/0x320 [idpf]
[ 3707.563739]  idpf_remove+0xbf/0x780 [idpf]
[ 3707.563769]  pci_device_remove+0xab/0x1e0
[ 3707.563786]  device_release_driver_internal+0x371/0x530
[ 3707.563803]  driver_detach+0xbf/0x180
[ 3707.563816]  bus_remove_driver+0x11b/0x2a0
[ 3707.563829]  pci_unregister_driver+0x2a/0x250

Introduce an error check and log the vport number and error code.
On removal make sure to check VPORT_REG_NETDEV flag prior to calling
unregister and free on the netdev.

Add local variables for idx, vport_config and netdev for readability.

Fixes: 0fe4546 ("idpf: add create vport and netdev configuration")
Suggested-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Samuel Salin <Samuel.salin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

Author: etantilov

drivers/net/ethernet/intel/idpf/idpf_lib.c

@@ -927,15 +927,19 @@ static int idpf_stop(struct net_device *netdev)
 static void idpf_decfg_netdev(struct idpf_vport *vport)
 {
 	struct idpf_adapter *adapter = vport->adapter;
+	u16 idx = vport->idx;
 
 	kfree(vport->rx_ptype_lkup);
 	vport->rx_ptype_lkup = NULL;
 
-	unregister_netdev(vport->netdev);
-	free_netdev(vport->netdev);
+	if (test_and_clear_bit(IDPF_VPORT_REG_NETDEV,
+			       adapter->vport_config[idx]->flags)) {
+		unregister_netdev(vport->netdev);
+		free_netdev(vport->netdev);
+	}
 	vport->netdev = NULL;
 
-	adapter->netdevs[vport->idx] = NULL;
+	adapter->netdevs[idx] = NULL;
 }
 
 /**
@@ -1536,13 +1540,22 @@ void idpf_init_task(struct work_struct *work)
 	}
 
 	for (index = 0; index < adapter->max_vports; index++) {
-		if (adapter->netdevs[index] &&
-		    !test_bit(IDPF_VPORT_REG_NETDEV,
-			      adapter->vport_config[index]->flags)) {
-			register_netdev(adapter->netdevs[index]);
-			set_bit(IDPF_VPORT_REG_NETDEV,
-				adapter->vport_config[index]->flags);
+		struct net_device *netdev = adapter->netdevs[index];
+		struct idpf_vport_config *vport_config;
+
+		vport_config = adapter->vport_config[index];
+
+		if (!netdev ||
+		    test_bit(IDPF_VPORT_REG_NETDEV, vport_config->flags))
+			continue;
+
+		err = register_netdev(netdev);
+		if (err) {
+			dev_err(&pdev->dev, "failed to register netdev for vport %d: %pe\n",
+				index, ERR_PTR(err));
+			continue;
 		}
+		set_bit(IDPF_VPORT_REG_NETDEV, vport_config->flags);
 	}
 
 	/* As all the required vports are created, clear the reset flag