From: Vitaly Lifshits <vitaly.lifshits@intel.com>
Date: Wed, 21 Oct 2020 14:59:37 +0300
Subject: e1000e: add rtnl_lock() to e1000_reset_task
Patch-mainline: v5.12-rc5
Git-commit: 21f857f0321d0d0ea9b1a758bd55dc63d1cb2437
References: git-fixes

A possible race condition was found in e1000_reset_task,
after discovering a similar issue in igb driver via
commit 024a8168b749 ("igb: reinit_locked() should be called
with rtnl_lock").

Added rtnl_lock() and rtnl_unlock() to avoid this.

Fixes: bc7f75fa9788 ("[E1000E]: New pci-express e1000 driver (currently for ICH9 devices only)")
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Vitaly Lifshits <vitaly.lifshits@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/intel/e1000e/netdev.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -5944,15 +5944,19 @@ static void e1000_reset_task(struct work
 	struct e1000_adapter *adapter;
 	adapter = container_of(work, struct e1000_adapter, reset_task);
 
+	rtnl_lock();
 	/* don't run the task if already down */
-	if (test_bit(__E1000_DOWN, &adapter->state))
+	if (test_bit(__E1000_DOWN, &adapter->state)) {
+		rtnl_unlock();
 		return;
+	}
 
 	if (!(adapter->flags & FLAG_RESTART_NOW)) {
 		e1000e_dump(adapter);
 		e_err("Reset adapter unexpectedly\n");
 	}
 	e1000e_reinit_locked(adapter);
+	rtnl_unlock();
 }
 
 /**