4.2-stable review patch. If anyone has any objections, please let me know.
------------------ From: "Lendacky, Thomas" <[email protected]> [ Upstream commit 20986ed826cbb36bb8f2d77f872e3c52d8d30647 ] During Tx cleanup it's still possible for the descriptor data to be read ahead of the descriptor index. A memory barrier is required between the read of the descriptor index and the start of the Tx cleanup loop. This allows a change to a lighter-weight barrier in the Tx transmit routine just before updating the current descriptor index. Since the memory barrier does result in extra overhead on arm64, keep the previous change to not chase the current descriptor value. This prevents the execution of the barrier for each loop performed. Suggested-by: Alexander Duyck <[email protected]> Signed-off-by: Tom Lendacky <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/net/ethernet/amd/xgbe/xgbe-dev.c | 2 +- drivers/net/ethernet/amd/xgbe/xgbe-drv.c | 4 ++++ 2 files changed, 5 insertions(+), 1 deletion(-) --- a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c +++ b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c @@ -1595,7 +1595,7 @@ static void xgbe_dev_xmit(struct xgbe_ch packet->rdesc_count, 1); /* Make sure ownership is written to the descriptor */ - wmb(); + smp_wmb(); ring->cur = cur_index + 1; if (!packet->skb->xmit_more || --- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c +++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c @@ -1816,6 +1816,10 @@ static int xgbe_tx_poll(struct xgbe_chan return 0; cur = ring->cur; + + /* Be sure we get ring->cur before accessing descriptor data */ + smp_rmb(); + txq = netdev_get_tx_queue(netdev, channel->queue_index); while ((processed < XGBE_TX_DESC_MAX_PROC) && -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
