4.4-stable review patch. If anyone has any objections, please let me know.
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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)