From 20a41fba679d665cdae2808e2b9cae97c073351f Mon Sep 17 00:00:00 2001 From: "Lendacky, Thomas" Date: Wed, 21 Oct 2015 15:37:05 -0500 Subject: [PATCH] amd-xgbe: Use wmb before updating current descriptor count The code currently uses the lightweight dma_wmb barrier before updating the current descriptor count. Under heavy load, the Tx cleanup routine was seeing the updated current descriptor count before the updated descriptor information. As a result, the Tx descriptor was being cleaned up before it was used because it was not "owned" by the hardware yet, resulting in a Tx queue hang. Using the wmb barrier insures that the descriptor is updated before the descriptor counter preventing the Tx queue hang. For extra insurance, the Tx cleanup routine is changed to grab the current decriptor count on entry and uses that initial value in the processing loop rather than trying to chase the current value. Signed-off-by: Tom Lendacky Tested-by: Christoffer Dall Signed-off-by: David S. Miller --- drivers/net/ethernet/amd/xgbe/xgbe-dev.c | 2 +- drivers/net/ethernet/amd/xgbe/xgbe-drv.c | 4 +++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c index a4473d8ff4fa..e9ab8b9f3b9c 100644 --- 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_channel *channel) packet->rdesc_count, 1); /* Make sure ownership is written to the descriptor */ - dma_wmb(); + wmb(); ring->cur = cur_index + 1; if (!packet->skb->xmit_more || diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c index aae9d5ecd182..d2b77d985441 100644 --- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c +++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c @@ -1807,6 +1807,7 @@ static int xgbe_tx_poll(struct xgbe_channel *channel) struct netdev_queue *txq; int processed = 0; unsigned int tx_packets = 0, tx_bytes = 0; + unsigned int cur; DBGPR("-->xgbe_tx_poll\n"); @@ -1814,10 +1815,11 @@ static int xgbe_tx_poll(struct xgbe_channel *channel) if (!ring) return 0; + cur = ring->cur; txq = netdev_get_tx_queue(netdev, channel->queue_index); while ((processed < XGBE_TX_DESC_MAX_PROC) && - (ring->dirty != ring->cur)) { + (ring->dirty != cur)) { rdata = XGBE_GET_DESC_DATA(ring, ring->dirty); rdesc = rdata->rdesc; -- 2.20.1