Merge branch 'for-davem' of git://git.kernel.org/pub/scm/linux/kernel/git/bwh/sfc-next

Ben Hutchings says:

====================
A single fix by Alexandre Rames for the recent changes to TSO.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/net_driver.h

@@ -141,6 +141,8 @@ struct efx_special_buffer {
  * @len: Length of this fragment.
  *	This field is zero when the queue slot is empty.
  * @unmap_len: Length of this fragment to unmap
+ * @dma_offset: Offset of @dma_addr from the address of the backing DMA mapping.
+ * Only valid if @unmap_len != 0.
  */
 struct efx_tx_buffer {
 	union {
@@ -154,6 +156,7 @@ struct efx_tx_buffer {
 	unsigned short flags;
 	unsigned short len;
 	unsigned short unmap_len;
+	unsigned short dma_offset;
 };
 #define EFX_TX_BUF_CONT		1	/* not last descriptor of packet */
 #define EFX_TX_BUF_SKB		2	/* buffer is last part of skb */

drivers/net/ethernet/sfc/tx.c

@@ -65,8 +65,7 @@ static void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
 {
 	if (buffer->unmap_len) {
 		struct device *dma_dev = &tx_queue->efx->pci_dev->dev;
-		dma_addr_t unmap_addr = (buffer->dma_addr + buffer->len -
-					 buffer->unmap_len);
+		dma_addr_t unmap_addr = buffer->dma_addr - buffer->dma_offset;
 		if (buffer->flags & EFX_TX_BUF_MAP_SINGLE)
 			dma_unmap_single(dma_dev, unmap_addr, buffer->unmap_len,
 					 DMA_TO_DEVICE);
@@ -414,6 +413,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 		/* Transfer ownership of the unmapping to the final buffer */
 		buffer->flags = EFX_TX_BUF_CONT | dma_flags;
 		buffer->unmap_len = unmap_len;
+		buffer->dma_offset = buffer->dma_addr - unmap_addr;
 		unmap_len = 0;
 
 		/* Get address and size of next fragment */
@@ -980,6 +980,7 @@ static int efx_tso_put_header(struct efx_tx_queue *tx_queue,
 			return -ENOMEM;
 		}
 		buffer->unmap_len = buffer->len;
+		buffer->dma_offset = 0;
 		buffer->flags |= EFX_TX_BUF_MAP_SINGLE;
 	}
 
@@ -1121,6 +1122,7 @@ static void tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue,
 	if (st->in_len == 0) {
 		/* Transfer ownership of the DMA mapping */
 		buffer->unmap_len = st->unmap_len;
+		buffer->dma_offset = buffer->unmap_len - buffer->len;
 		buffer->flags |= st->dma_flags;
 		st->unmap_len = 0;
 	}
@@ -1219,6 +1221,7 @@ static int tso_start_new_packet(struct efx_tx_queue *tx_queue,
 		if (is_last) {
 			buffer->flags = EFX_TX_BUF_CONT | EFX_TX_BUF_MAP_SINGLE;
 			buffer->unmap_len = st->header_unmap_len;
+			buffer->dma_offset = 0;
 			/* Ensure we only unmap them once in case of a
 			 * later DMA mapping error and rollback
 			 */