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

This patch fixes an issue seen on Power systems with ixgbe which results in skb list corruption and an eventual kernel oops. The following is what was observed:

CPU 1 CPU2 ============================ ============================ 1: ixgbe_xmit_frame_ring ixgbe_clean_tx_irq 2: first->skb = skb eop_desc = tx_buffer->next_to_watch 3: ixgbe_tx_map read_barrier_depends() 4: wmb check adapter written status bit 5: first->next_to_watch = tx_desc napi_consume_skb(tx_buffer->skb ..); 6: writel(i, tx_ring->tail);

The read_barrier_depends is insufficient to ensure that tx_buffer->skb does not get loaded prior to tx_buffer->next_to_watch, which then results in loading a stale skb pointer. This patch replaces the read_barrier_depends with smp_rmb to ensure loads are ordered with respect to the load of tx_buffer->next_to_watch.

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 --- drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c index ca06c3cc2ca8..62a18914f00f 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c @@ -1192,7 +1192,7 @@ static bool ixgbe_clean_tx_irq(struct ixgbe_q_vector *q_vector, 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(IXGBE_TXD_STAT_DD)))