[Intel-wired-lan] [PATCH v2 1/2] igb: Use device_lock() insead of rtnl_lock()

[Intel-wired-lan] [PATCH v2 1/2] igb: Use device_lock() insead of rtnl_lock()

[Kai-Heng Feng]

Commit 9474933caf21 ("igb: close/suspend race in netif_device_detach")
fixed race condition between close and power management ops by using
rtnl_lock().

However we can achieve the same by using device_lock() since all power
management ops are protected by device_lock().

This fix is a preparation for next patch, to prevent a dead lock under
rtnl_lock() when calling runtime resume routine.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v2:
 - No change.

 drivers/net/ethernet/intel/igb/igb_main.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index b46bff8fe056..3750e2b926b1 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -4026,8 +4026,13 @@ static int __igb_close(struct net_device *netdev, bool suspending)
 
 int igb_close(struct net_device *netdev)
 {
+	struct igb_adapter *adapter = netdev_priv(netdev);
+	struct device *dev = &adapter->pdev->dev;
+
+	device_lock(dev);
 	if (netif_device_present(netdev) || netdev->dismantle)
 		return __igb_close(netdev, false);
+	device_unlock(dev);
 	return 0;
 }
 
@@ -8760,7 +8765,6 @@ static int __igb_shutdown(struct pci_dev *pdev, bool *enable_wake,
 	u32 wufc = runtime ? E1000_WUFC_LNKC : adapter->wol;
 	bool wake;
 
-	rtnl_lock();
 	netif_device_detach(netdev);
 
 	if (netif_running(netdev))
@@ -8769,7 +8773,6 @@ static int __igb_shutdown(struct pci_dev *pdev, bool *enable_wake,
 	igb_ptp_suspend(adapter);
 
 	igb_clear_interrupt_scheme(adapter);
-	rtnl_unlock();
 
 	status = rd32(E1000_STATUS);
 	if (status & E1000_STATUS_LU)
@@ -8897,13 +8900,11 @@ static int __maybe_unused igb_resume(struct device *dev)
 
 	wr32(E1000_WUS, ~0);
 
-	rtnl_lock();
 	if (!err && netif_running(netdev))
 		err = __igb_open(netdev, true);
 
 	if (!err)
 		netif_device_attach(netdev);
-	rtnl_unlock();
 
 	return err;
 }
-- 
2.17.1

[Intel-wired-lan] [PATCH v2 1/2] igb: Use device_lock() insead of rtnl_lock()

[Dan Carpenter]

Hi Kai-Heng,

url:    https://github.com/0day-ci/linux/commits/Kai-Heng-Feng/igb-Use-device_lock-insead-of-rtnl_lock/20200205-174208
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/next-queue.git dev-queue

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

New smatch warnings:
drivers/net/ethernet/intel/igb/igb_main.c:4036 igb_close() warn: inconsistent returns 'dev->mutex'.

# https://github.com/0day-ci/linux/commit/905877ae7d44efc1d9c5c1ae9f4489f56bcb13a6
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 905877ae7d44efc1d9c5c1ae9f4489f56bcb13a6
vim +4036 drivers/net/ethernet/intel/igb/igb_main.c

9d5c824399dea8 drivers/net/igb/igb_main.c                Auke Kok       2008-01-24  4026  
46eafa59e18d03 drivers/net/ethernet/intel/igb/igb_main.c Stefan Assmann 2016-02-03  4027  int igb_close(struct net_device *netdev)
749ab2cd127046 drivers/net/ethernet/intel/igb/igb_main.c Yan, Zheng     2012-01-04  4028  {
905877ae7d44ef drivers/net/ethernet/intel/igb/igb_main.c Kai-Heng Feng  2020-02-05  4029  	struct igb_adapter *adapter = netdev_priv(netdev);
905877ae7d44ef drivers/net/ethernet/intel/igb/igb_main.c Kai-Heng Feng  2020-02-05  4030  	struct device *dev = &adapter->pdev->dev;
905877ae7d44ef drivers/net/ethernet/intel/igb/igb_main.c Kai-Heng Feng  2020-02-05  4031  
905877ae7d44ef drivers/net/ethernet/intel/igb/igb_main.c Kai-Heng Feng  2020-02-05  4032  	device_lock(dev);
888f22931478a0 drivers/net/ethernet/intel/igb/igb_main.c Lyude Paul     2017-12-12  4033  	if (netif_device_present(netdev) || netdev->dismantle)
749ab2cd127046 drivers/net/ethernet/intel/igb/igb_main.c Yan, Zheng     2012-01-04  4034  		return __igb_close(netdev, false);
                                                                                                        ^^^^^^
Lock held for this return.

905877ae7d44ef drivers/net/ethernet/intel/igb/igb_main.c Kai-Heng Feng  2020-02-05  4035  	device_unlock(dev);
9474933caf21a4 drivers/net/ethernet/intel/igb/igb_main.c Todd Fujinaka  2016-11-15 @4036  	return 0;
749ab2cd127046 drivers/net/ethernet/intel/igb/igb_main.c Yan, Zheng     2012-01-04  4037  }
749ab2cd127046 drivers/net/ethernet/intel/igb/igb_main.c Yan, Zheng     2012-01-04  4038  

---
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