sfc: remove Software TSO

It gives no advantage over GSO now that xmit_more exists.  If we find
 ourselves unable to handle a TSO skb (because our TXQ doesn't have a
 TSOv2 context and the NIC doesn't support TSOv1), hand it back to GSO.
 Also do that if the TSO handler fails with EINVAL for any other reason.
As Falcon-architecture NICs don't support any firmware-assisted TSO,
 they no longer advertise TSO feature flags at all.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/ef10.c

@@ -2158,6 +2158,20 @@ static int efx_ef10_tx_tso_desc(struct efx_tx_queue *tx_queue,
 	return 0;
 }
 
+static u32 efx_ef10_tso_versions(struct efx_nic *efx)
+{
+	struct efx_ef10_nic_data *nic_data = efx->nic_data;
+	u32 tso_versions = 0;
+
+	if (nic_data->datapath_caps &
+	    (1 << MC_CMD_GET_CAPABILITIES_OUT_TX_TSO_LBN))
+		tso_versions |= BIT(1);
+	if (nic_data->datapath_caps2 &
+	    (1 << MC_CMD_GET_CAPABILITIES_V2_OUT_TX_TSO_V2_LBN))
+		tso_versions |= BIT(2);
+	return tso_versions;
+}
+
 static void efx_ef10_tx_init(struct efx_tx_queue *tx_queue)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_INIT_TXQ_IN_LEN(EFX_MAX_DMAQ_SIZE * 8 /
@@ -5759,6 +5773,7 @@ const struct efx_nic_type efx_hunt_a0_nic_type = {
 #endif
 	.get_mac_address = efx_ef10_get_mac_address_pf,
 	.set_mac_address = efx_ef10_set_mac_address,
+	.tso_versions = efx_ef10_tso_versions,
 
 	.revision = EFX_REV_HUNT_A0,
 	.max_dma_mask = DMA_BIT_MASK(ESF_DZ_TX_KER_BUF_ADDR_WIDTH),

drivers/net/ethernet/sfc/efx.c

@@ -3200,23 +3200,6 @@ static int efx_pci_probe(struct pci_dev *pci_dev,
 	efx = netdev_priv(net_dev);
 	efx->type = (const struct efx_nic_type *) entry->driver_data;
 	efx->fixed_features |= NETIF_F_HIGHDMA;
-	net_dev->features |= (efx->type->offload_features | NETIF_F_SG |
-			      NETIF_F_TSO | NETIF_F_RXCSUM);
-	if (efx->type->offload_features & (NETIF_F_IPV6_CSUM | NETIF_F_HW_CSUM))
-		net_dev->features |= NETIF_F_TSO6;
-	/* Mask for features that also apply to VLAN devices */
-	net_dev->vlan_features |= (NETIF_F_HW_CSUM | NETIF_F_SG |
-				   NETIF_F_HIGHDMA | NETIF_F_ALL_TSO |
-				   NETIF_F_RXCSUM);
-
-	net_dev->hw_features = net_dev->features & ~efx->fixed_features;
-
-	/* Disable VLAN filtering by default.  It may be enforced if
-	 * the feature is fixed (i.e. VLAN filters are required to
-	 * receive VLAN tagged packets due to vPort restrictions).
-	 */
-	net_dev->features &= ~NETIF_F_HW_VLAN_CTAG_FILTER;
-	net_dev->features |= efx->fixed_features;
 
 	pci_set_drvdata(pci_dev, efx);
 	SET_NETDEV_DEV(net_dev, &pci_dev->dev);
@@ -3239,6 +3222,27 @@ static int efx_pci_probe(struct pci_dev *pci_dev,
 	if (rc)
 		goto fail3;
 
+	net_dev->features |= (efx->type->offload_features | NETIF_F_SG |
+			      NETIF_F_TSO | NETIF_F_RXCSUM);
+	if (efx->type->offload_features & (NETIF_F_IPV6_CSUM | NETIF_F_HW_CSUM))
+		net_dev->features |= NETIF_F_TSO6;
+	/* Check whether device supports TSO */
+	if (!efx->type->tso_versions || !efx->type->tso_versions(efx))
+		net_dev->features &= ~NETIF_F_ALL_TSO;
+	/* Mask for features that also apply to VLAN devices */
+	net_dev->vlan_features |= (NETIF_F_HW_CSUM | NETIF_F_SG |
+				   NETIF_F_HIGHDMA | NETIF_F_ALL_TSO |
+				   NETIF_F_RXCSUM);
+
+	net_dev->hw_features = net_dev->features & ~efx->fixed_features;
+
+	/* Disable VLAN filtering by default.  It may be enforced if
+	 * the feature is fixed (i.e. VLAN filters are required to
+	 * receive VLAN tagged packets due to vPort restrictions).
+	 */
+	net_dev->features &= ~NETIF_F_HW_VLAN_CTAG_FILTER;
+	net_dev->features |= efx->fixed_features;
+
 	rc = efx_register_netdev(efx);
 	if (rc)
 		goto fail4;

drivers/net/ethernet/sfc/ethtool.c

@@ -69,6 +69,7 @@ static const struct efx_sw_stat_desc efx_sw_stat_desc[] = {
 	EFX_ETHTOOL_UINT_TXQ_STAT(tso_bursts),
 	EFX_ETHTOOL_UINT_TXQ_STAT(tso_long_headers),
 	EFX_ETHTOOL_UINT_TXQ_STAT(tso_packets),
+	EFX_ETHTOOL_UINT_TXQ_STAT(tso_fallbacks),
 	EFX_ETHTOOL_UINT_TXQ_STAT(pushes),
 	EFX_ETHTOOL_UINT_TXQ_STAT(pio_packets),
 	EFX_ETHTOOL_UINT_TXQ_STAT(cb_packets),

drivers/net/ethernet/sfc/net_driver.h

@@ -225,6 +225,7 @@ struct efx_tx_buffer {
  * @tso_long_headers: Number of packets with headers too long for standard
  *	blocks
  * @tso_packets: Number of packets via the TSO xmit path
+ * @tso_fallbacks: Number of times TSO fallback used
  * @pushes: Number of times the TX push feature has been used
  * @pio_packets: Number of times the TX PIO feature has been used
  * @xmit_more_available: Are any packets waiting to be pushed to the NIC
@@ -266,6 +267,7 @@ struct efx_tx_queue {
 	unsigned int tso_bursts;
 	unsigned int tso_long_headers;
 	unsigned int tso_packets;
+	unsigned int tso_fallbacks;
 	unsigned int pushes;
 	unsigned int pio_packets;
 	bool xmit_more_available;
@@ -1225,6 +1227,8 @@ struct efx_mtd_partition {
  *	and tx_type will already have been validated but this operation
  *	must validate and update rx_filter.
  * @set_mac_address: Set the MAC address of the device
+ * @tso_versions: Returns mask of firmware-assisted TSO versions supported.
+ *	If %NULL, then device does not support any TSO version.
  * @revision: Hardware architecture revision
  * @txd_ptr_tbl_base: TX descriptor ring base address
  * @rxd_ptr_tbl_base: RX descriptor ring base address
@@ -1381,6 +1385,7 @@ struct efx_nic_type {
 	void (*vswitching_remove)(struct efx_nic *efx);
 	int (*get_mac_address)(struct efx_nic *efx, unsigned char *perm_addr);
 	int (*set_mac_address)(struct efx_nic *efx);
+	u32 (*tso_versions)(struct efx_nic *efx);
 
 	int revision;
 	unsigned int txd_ptr_tbl_base;

drivers/net/ethernet/sfc/tx.c

@@ -446,10 +446,38 @@ static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue)
 	}
 }
 
-static int efx_tx_tso_sw(struct efx_tx_queue *tx_queue, struct sk_buff *skb,
-			 bool *data_mapped)
+/*
+ * Fallback to software TSO.
+ *
+ * This is used if we are unable to send a GSO packet through hardware TSO.
+ * This should only ever happen due to per-queue restrictions - unsupported
+ * packets should first be filtered by the feature flags.
+ *
+ * Returns 0 on success, error code otherwise.
+ */
+static int efx_tx_tso_fallback(struct efx_tx_queue *tx_queue,
+			       struct sk_buff *skb)
 {
-	return efx_enqueue_skb_tso(tx_queue, skb, data_mapped);
+	struct sk_buff *segments, *next;
+
+	segments = skb_gso_segment(skb, 0);
+	if (IS_ERR(segments))
+		return PTR_ERR(segments);
+
+	dev_kfree_skb_any(skb);
+	skb = segments;
+
+	while (skb) {
+		next = skb->next;
+		skb->next = NULL;
+
+		if (next)
+			skb->xmit_more = true;
+		efx_enqueue_skb(tx_queue, skb);
+		skb = next;
+	}
+
+	return 0;
 }
 
 /*
@@ -473,6 +501,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 	bool data_mapped = false;
 	unsigned int segments;
 	unsigned int skb_len;
+	int rc;
 
 	skb_len = skb->len;
 	segments = skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 0;
@@ -485,7 +514,14 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 	 */
 	if (segments) {
 		EFX_BUG_ON_PARANOID(!tx_queue->handle_tso);
-		if (tx_queue->handle_tso(tx_queue, skb, &data_mapped))
+		rc = tx_queue->handle_tso(tx_queue, skb, &data_mapped);
+		if (rc == -EINVAL) {
+			rc = efx_tx_tso_fallback(tx_queue, skb);
+			tx_queue->tso_fallbacks++;
+			if (rc == 0)
+				return 0;
+		}
+		if (rc)
 			goto err;
 #ifdef EFX_USE_PIO
 	} else if (skb_len <= efx_piobuf_size && !skb->xmit_more &&
@@ -801,7 +837,7 @@ void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
 	/* Set up default function pointers. These may get replaced by
 	 * efx_nic_init_tx() based off NIC/queue capabilities.
 	 */
-	tx_queue->handle_tso = efx_tx_tso_sw;
+	tx_queue->handle_tso = efx_enqueue_skb_tso;
 
 	/* Some older hardware requires Tx writes larger than 32. */
 	tx_queue->tx_min_size = EFX_WORKAROUND_15592(efx) ? 33 : 0;