From 5449e27167c9945d24108690aff86943d79774a7 Mon Sep 17 00:00:00 2001 From: "Lendacky, Thomas" Date: Thu, 20 Nov 2014 11:03:26 -0600 Subject: [PATCH] amd-xgbe: Add a read memory barrier to Tx/Rx path Add a read memory barrier to the Tx and Rx paths where the ownership bit is checked to be sure that all descriptor fields are read after having read the ownership bit for the descriptor. This has not been an issue to date, but it's a good safe-guard to have. Signed-off-by: Tom Lendacky Signed-off-by: David S. Miller --- drivers/net/ethernet/amd/xgbe/xgbe-dev.c | 3 +++ drivers/net/ethernet/amd/xgbe/xgbe-drv.c | 4 ++++ 2 files changed, 7 insertions(+) diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c index f6014d330b2e..9b1d9fa68257 100644 --- a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c +++ b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c @@ -1558,6 +1558,9 @@ static int xgbe_dev_read(struct xgbe_channel *channel) if (XGMAC_GET_BITS_LE(rdesc->desc3, RX_NORMAL_DESC3, OWN)) return 1; + /* Make sure descriptor fields are read after reading the OWN bit */ + rmb(); + #ifdef XGMAC_ENABLE_RX_DESC_DUMP xgbe_dump_rx_desc(ring, rdesc, ring->cur); #endif diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c index 0544931329d1..eebb787251c4 100644 --- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c +++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c @@ -1791,6 +1791,10 @@ static int xgbe_tx_poll(struct xgbe_channel *channel) if (!hw_if->tx_complete(rdesc)) break; + /* Make sure descriptor fields are read after reading the OWN + * bit */ + rmb(); + #ifdef XGMAC_ENABLE_TX_DESC_DUMP xgbe_dump_tx_desc(ring, ring->dirty, 1, 0); #endif -- 2.20.1