From 2abb802779b6dca5bafa8a16923ea222189a35cc Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Thu, 20 Dec 2012 18:48:20 +0000 Subject: [PATCH] sfc: Properly sync RX DMA buffer when it is not the last in the page [ Upstream commit 3a68f19d7afb80f548d016effbc6ed52643a8085 ] We may currently allocate two RX DMA buffers to a page, and only unmap the page when the second is completed. We do not sync the first RX buffer to be completed; this can result in packet loss or corruption if the last RX buffer completed in a NAPI poll is the first in a page and is not DMA-coherent. (In the middle of a NAPI poll, we will handle the following RX completion and unmap the page *before* looking at the content of the first buffer.) Signed-off-by: Ben Hutchings [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- drivers/net/ethernet/sfc/rx.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c index 5ef4cc002b7d..b4d3cd54c621 100644 --- a/drivers/net/ethernet/sfc/rx.c +++ b/drivers/net/ethernet/sfc/rx.c @@ -246,7 +246,8 @@ static int efx_init_rx_buffers_page(struct efx_rx_queue *rx_queue) } static void efx_unmap_rx_buffer(struct efx_nic *efx, - struct efx_rx_buffer *rx_buf) + struct efx_rx_buffer *rx_buf, + unsigned int used_len) { if (rx_buf->is_page && rx_buf->u.page) { struct efx_rx_page_state *state; @@ -257,6 +258,10 @@ static void efx_unmap_rx_buffer(struct efx_nic *efx, state->dma_addr, efx_rx_buf_size(efx), PCI_DMA_FROMDEVICE); + } else if (used_len) { + dma_sync_single_for_cpu(&efx->pci_dev->dev, + rx_buf->dma_addr, used_len, + DMA_FROM_DEVICE); } } else if (!rx_buf->is_page && rx_buf->u.skb) { pci_unmap_single(efx->pci_dev, rx_buf->dma_addr, @@ -279,7 +284,7 @@ static void efx_free_rx_buffer(struct efx_nic *efx, static void efx_fini_rx_buffer(struct efx_rx_queue *rx_queue, struct efx_rx_buffer *rx_buf) { - efx_unmap_rx_buffer(rx_queue->efx, rx_buf); + efx_unmap_rx_buffer(rx_queue->efx, rx_buf, 0); efx_free_rx_buffer(rx_queue->efx, rx_buf); } @@ -550,10 +555,10 @@ void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index, goto out; } - /* Release card resources - assumes all RX buffers consumed in-order - * per RX queue + /* Release and/or sync DMA mapping - assumes all RX buffers + * consumed in-order per RX queue */ - efx_unmap_rx_buffer(efx, rx_buf); + efx_unmap_rx_buffer(efx, rx_buf, len); /* Prefetch nice and early so data will (hopefully) be in cache by * the time we look at it. -- 2.39.2