igbvf: Use smp_rmb rather than read_barrier_depends

commit 1e1f9ca546556e508d021545861f6b5fc75a95fe upstream.

The original issue being fixed in this patch was seen with the ixgbe
driver, but the same issue exists with igbvf 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: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/net/ethernet/intel/igbvf/netdev.c b/drivers/net/ethernet/intel/igbvf/netdev.c
index d608599e123a9d8634905c607faac60da85618f6..296559052d451454a573b6c22fdf5bbdc24e7915 100644 (file)
--- a/drivers/net/ethernet/intel/igbvf/netdev.c
+++ b/drivers/net/ethernet/intel/igbvf/netdev.c
@@ -808,7 +808,7 @@ static bool igbvf_clean_tx_irq(struct igbvf_ring *tx_ring)
                        break;
 
                /* prevent any other reads prior to eop_desc */
-               read_barrier_depends();
+               smp_rmb();
 
                /* if DD is not set pending work has not been completed */
                if (!(eop_desc->wb.status & cpu_to_le32(E1000_TXD_STAT_DD)))