igc: fix deadlock caused by taking RTNL in RPM resume path

It was reported a RTNL deadlock in the igc driver that was causing
problems during suspend/resume.

The solution is similar to commit ac8c58f ("igb: fix deadlock
caused by taking RTNL in RPM resume path").

Reported-by: James Hogan <jhogan@kernel.org>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>

drivers/net/ethernet/intel/igc/igc_main.c

@@ -6638,7 +6638,7 @@ static void igc_deliver_wake_packet(struct net_device *netdev)
 	netif_rx(skb);
 }
 
-static int __maybe_unused igc_resume(struct device *dev)
+static int __maybe_unused __igc_resume(struct device *dev, bool rpm)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct net_device *netdev = pci_get_drvdata(pdev);
@@ -6680,23 +6680,30 @@ static int __maybe_unused igc_resume(struct device *dev)
 
 	wr32(IGC_WUS, ~0);
 
-	rtnl_lock();
+	if (!rpm)
+		rtnl_lock();
 	if (!err && netif_running(netdev))
 		err = __igc_open(netdev, true);
 
 	if (!err)
 		netif_device_attach(netdev);
-	rtnl_unlock();
+	if (!rpm)
+		rtnl_unlock();
 
 	return err;
 }
 
 static int __maybe_unused igc_runtime_resume(struct device *dev)
 {
-	return igc_resume(dev);
+	return __igc_resume(dev, true);
+}
+
+static int __maybe_unused igc_resume(struct device *dev)
+{
+	return __igc_resume(dev, false);
 }
 
-static int __maybe_unused igc_suspend(struct device *dev)
+static int __maybe_unused __igc_suspend(struct device *dev)
 {
 	return __igc_shutdown(to_pci_dev(dev), NULL, 0);
 }
@@ -6757,7 +6764,7 @@ static pci_ers_result_t igc_io_error_detected(struct pci_dev *pdev,
  *  @pdev: Pointer to PCI device
  *
  *  Restart the card from scratch, as if from a cold-boot. Implementation
- *  resembles the first-half of the igc_resume routine.
+ *  resembles the first-half of the __igc_resume routine.
  **/
 static pci_ers_result_t igc_io_slot_reset(struct pci_dev *pdev)
 {
@@ -6796,7 +6803,7 @@ static pci_ers_result_t igc_io_slot_reset(struct pci_dev *pdev)
  *
  *  This callback is called when the error recovery driver tells us that
  *  its OK to resume normal operation. Implementation resembles the
- *  second-half of the igc_resume routine.
+ *  second-half of the __igc_resume routine.
  */
 static void igc_io_resume(struct pci_dev *pdev)
 {