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 52c6912fde0133981ee50ba08808f257829c4c93 upstream.
The original issue being fixed in this patch was seen with the ixgbe driver, but the same issue exists with i40e 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/i40e/i40e_main.c | 2 +- drivers/net/ethernet/intel/i40e/i40e_txrx.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c @@ -3595,7 +3595,7 @@ static bool i40e_clean_fdir_tx_irq(struc break;
/* prevent any other reads prior to eop_desc */ - read_barrier_depends(); + smp_rmb();
/* if the descriptor isn't done, no work yet to do */ if (!(eop_desc->cmd_type_offset_bsz & --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c @@ -663,7 +663,7 @@ 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)