From: Brian King <brking@linux.vnet.ibm.com>
Date: Fri, 17 Nov 2017 11:05:49 -0600
Subject: i40evf: Use smp_rmb rather than read_barrier_depends
Patch-mainline: v4.15-rc1
Git-commit: f72271e2a0ae4277d53c4053f5eed8bb346ba38a
References: bsc#1056658 FATE#322188 bsc#1056662 FATE#322186

The original issue being fixed in this patch was seen with the ixgbe
driver, but the same issue exists with i40evf as well, as the code is
very similar. read_barrier_depends is not sufficient to ensure
loads following it are not speculatively loaded out of order
by the CPU, which can result in stale data being loaded, causing
potential system crashes.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/intel/i40evf/i40e_txrx.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
@@ -179,7 +179,7 @@ static bool i40e_clean_tx_irq(struct i40
 			break;
 
 		/* prevent any other reads prior to eop_desc */
-		read_barrier_depends();
+		smp_rmb();
 
 		i40e_trace(clean_tx_irq, tx_ring, tx_desc, tx_buf);
 		/* if the descriptor isn't done, no work yet to do */