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

[Vinicius Costa Gomes <vinicius.gomes@intel.com>]

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

The solution is similar to commit ac8c58f5b535 ("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>
---
Hi James,

Thanks to your investigation I found commit ac8c58f5b535, and it looks
like it could solve the issue you are seeing.

Could you please see if this patch helps. It's only compile and boot
tested.

Sorry the delay, I am travelling.

Cheers,


 drivers/net/ethernet/intel/igc/igc_main.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index ebff0e04045d..5079dc581d8d 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -6600,7 +6600,7 @@ 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);
@@ -6642,23 +6642,30 @@ 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_suspend(struct device *dev)
+static int __maybe_unused igc_resume(struct device *dev)
+{
+	return __igc_resume(dev, false);
+}
+
+static int __maybe_unused __igc_suspend(struct device *dev)
 {
 	return __igc_shutdown(to_pci_dev(dev), NULL, 0);
 }
@@ -6719,7 +6726,7 @@ 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)
 {
@@ -6758,7 +6765,7 @@ 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)
 {
-- 
2.37.1