net: mvpp2: do not unmap TSO headers buffers

The TSO header buffers are coming from a per cpu pool and should not
be unmapped as they are reused. The PPv2 driver was unmapping all
descriptors buffers unconditionally. This patch fixes this by checking
the buffers dma addresses before unmapping them, and by not unmapping
those who are located in the TSO header pool.

Fixes: 186cd4d4e414 ("net: mvpp2: software tso support")
Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/mvpp2.c

@@ -1167,6 +1167,11 @@ struct mvpp2_bm_pool {
 	u32 port_map;
 };
 
+#define IS_TSO_HEADER(txq_pcpu, addr) \
+	((addr) >= (txq_pcpu)->tso_headers_dma && \
+	 (addr) < (txq_pcpu)->tso_headers_dma + \
+	 (txq_pcpu)->size * TSO_HEADER_SIZE)
+
 /* Queue modes */
 #define MVPP2_QDIST_SINGLE_MODE	0
 #define MVPP2_QDIST_MULTI_MODE	1
@@ -5321,8 +5326,9 @@ static void mvpp2_txq_bufs_free(struct mvpp2_port *port,
 		struct mvpp2_txq_pcpu_buf *tx_buf =
 			txq_pcpu->buffs + txq_pcpu->txq_get_index;
 
-		dma_unmap_single(port->dev->dev.parent, tx_buf->dma,
-				 tx_buf->size, DMA_TO_DEVICE);
+		if (!IS_TSO_HEADER(txq_pcpu, tx_buf->dma))
+			dma_unmap_single(port->dev->dev.parent, tx_buf->dma,
+					 tx_buf->size, DMA_TO_DEVICE);
 		if (tx_buf->skb)
 			dev_kfree_skb_any(tx_buf->skb);
 
@@ -6212,12 +6218,15 @@ static inline void
 tx_desc_unmap_put(struct mvpp2_port *port, struct mvpp2_tx_queue *txq,
 		  struct mvpp2_tx_desc *desc)
 {
+	struct mvpp2_txq_pcpu *txq_pcpu = this_cpu_ptr(txq->pcpu);
+
 	dma_addr_t buf_dma_addr =
 		mvpp2_txdesc_dma_addr_get(port, desc);
 	size_t buf_sz =
 		mvpp2_txdesc_size_get(port, desc);
-	dma_unmap_single(port->dev->dev.parent, buf_dma_addr,
-			 buf_sz, DMA_TO_DEVICE);
+	if (!IS_TSO_HEADER(txq_pcpu, buf_dma_addr))
+		dma_unmap_single(port->dev->dev.parent, buf_dma_addr,
+				 buf_sz, DMA_TO_DEVICE);
 	mvpp2_txq_desc_put(txq);
 }