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Commit 3a68f19d authored by Ben Hutchings's avatar Ben Hutchings
Browse files

sfc: Properly sync RX DMA buffer when it is not the last in the page 



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: default avatarBen Hutchings <bhutchings@solarflare.com>
parent eb970ff0

drivers/net/ethernet/sfc/rx.c

+10 −5
Original line number Diff line number Diff line
@@ -236,7 +236,8 @@ 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->flags & EFX_RX_BUF_PAGE) && rx_buf->u.page) {

		struct efx_rx_page_state *state;
@@ -247,6 +248,10 @@ static void efx_unmap_rx_buffer(struct efx_nic *efx, 
				       state->dma_addr,

				       efx_rx_buf_size(efx),

				       DMA_FROM_DEVICE);

		} 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->flags & EFX_RX_BUF_PAGE) && rx_buf->u.skb) {

		dma_unmap_single(&efx->pci_dev->dev, rx_buf->dma_addr,
@@ -269,7 +274,7 @@ 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);

}
@@ -535,10 +540,10 @@ 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.