Patch "i40evf: Use smp_rmb rather than read_barrier_depends" has been added to the 4.4-stable tree

Patch "i40evf: Use smp_rmb rather than read_barrier_depends" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    i40evf: Use smp_rmb rather than read_barrier_depends

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     i40evf-use-smp_rmb-rather-than-read_barrier_depends.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From f72271e2a0ae4277d53c4053f5eed8bb346ba38a Mon Sep 17 00:00:00 2001
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

From: Brian King <brking@linux.vnet.ibm.com>

commit f72271e2a0ae4277d53c4053f5eed8bb346ba38a upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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
@@ -172,7 +172,7 @@ static bool i40e_clean_tx_irq(struct i40
 			break;
 
 		/* prevent any other reads prior to eop_desc */
-		read_barrier_depends();
+		smp_rmb();
 
 		/* we have caught up to head, no work left to do */
 		if (tx_head == tx_desc)


Patches currently in stable-queue which might be from brking@linux.vnet.ibm.com are

queue-4.4/i40evf-use-smp_rmb-rather-than-read_barrier_depends.patch
queue-4.4/igb-use-smp_rmb-rather-than-read_barrier_depends.patch
queue-4.4/ixgbevf-use-smp_rmb-rather-than-read_barrier_depends.patch
queue-4.4/igbvf-use-smp_rmb-rather-than-read_barrier_depends.patch
queue-4.4/fm10k-use-smp_rmb-rather-than-read_barrier_depends.patch
queue-4.4/ixgbe-fix-skb-list-corruption-on-power-systems.patch
queue-4.4/i40e-use-smp_rmb-rather-than-read_barrier_depends.patch