ibmveth: Add scatter-gather support

ibmveth can scatter gather up to 6 segments. If we go over this then
we have no option but to call skb_linearize, like other drivers with
similar limitations do.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Santiago Leon <santil@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 124 insertions, 60 deletions

diff --git a/drivers/net/ibmveth.c b/drivers/net/ibmveth.c
index aedcb180218..d8a89846c6a 100644
--- a/drivers/net/ibmveth.c
+++ b/drivers/net/ibmveth.c
@@ -897,6 +897,7 @@ static const struct ethtool_ops netdev_ethtool_ops = {
         .get_strings            = ibmveth_get_strings,
         .get_sset_count         = ibmveth_get_sset_count,
         .get_ethtool_stats      = ibmveth_get_ethtool_stats,
+        .set_sg                 = ethtool_op_set_sg,
 };
 
 static int ibmveth_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
@@ -906,96 +907,158 @@ static int ibmveth_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 
 #define page_offset(v) ((unsigned long)(v) & ((1 << 12) - 1))
 
-static netdev_tx_t ibmveth_start_xmit(struct sk_buff *skb,
-                                      struct net_device *netdev)
+static int ibmveth_send(struct ibmveth_adapter *adapter,
+                        union ibmveth_buf_desc *descs)
 {
-        struct ibmveth_adapter *adapter = netdev_priv(netdev);
-        union ibmveth_buf_desc desc;
-        unsigned long lpar_rc;
         unsigned long correlator;
         unsigned int retry_count;
-        unsigned int tx_dropped = 0;
-        unsigned int tx_bytes = 0;
-        unsigned int tx_packets = 0;
-        unsigned int tx_send_failed = 0;
-        unsigned int tx_map_failed = 0;
-        int used_bounce = 0;
-        unsigned long data_dma_addr;
+        unsigned long ret;
+
+        /*
+         * The retry count sets a maximum for the number of broadcast and
+         * multicast destinations within the system.
+         */
+        retry_count = 1024;
+        correlator = 0;
+        do {
+                ret = h_send_logical_lan(adapter->vdev->unit_address,
+                                             descs[0].desc, descs[1].desc,
+                                             descs[2].desc, descs[3].desc,
+                                             descs[4].desc, descs[5].desc,
+                                             correlator, &correlator);
+        } while ((ret == H_BUSY) && (retry_count--));
+
+        if (ret != H_SUCCESS && ret != H_DROPPED) {
+                ibmveth_error_printk("tx: h_send_logical_lan failed with "
+                                     "rc=%ld\n", ret);
+                return 1;
+        }
+
+        return 0;
+}
 
-        desc.fields.flags_len = IBMVETH_BUF_VALID | skb->len;
+static netdev_tx_t ibmveth_start_xmit(struct sk_buff *skb,
+                                      struct net_device *netdev)
+{
+        struct ibmveth_adapter *adapter = netdev_priv(netdev);
+        unsigned int desc_flags;
+        union ibmveth_buf_desc descs[6];
+        int last, i;
+        int force_bounce = 0;
+
+        /*
+         * veth handles a maximum of 6 segments including the header, so
+         * we have to linearize the skb if there are more than this.
+         */
+        if (skb_shinfo(skb)->nr_frags > 5 && __skb_linearize(skb)) {
+                netdev->stats.tx_dropped++;
+                goto out;
+        }
 
+        /* veth can't checksum offload UDP */
         if (skb->ip_summed == CHECKSUM_PARTIAL &&
             ip_hdr(skb)->protocol != IPPROTO_TCP && skb_checksum_help(skb)) {
                 ibmveth_error_printk("tx: failed to checksum packet\n");
-                tx_dropped++;
+                netdev->stats.tx_dropped++;
                 goto out;
         }
 
+        desc_flags = IBMVETH_BUF_VALID;
+
         if (skb->ip_summed == CHECKSUM_PARTIAL) {
-                unsigned char *buf = skb_transport_header(skb) + skb->csum_offset;
+                unsigned char *buf = skb_transport_header(skb) +
+                                                skb->csum_offset;
 
-                desc.fields.flags_len |= (IBMVETH_BUF_NO_CSUM | IBMVETH_BUF_CSUM_GOOD);
+                desc_flags |= (IBMVETH_BUF_NO_CSUM | IBMVETH_BUF_CSUM_GOOD);
 
                 /* Need to zero out the checksum */
                 buf[0] = 0;
                 buf[1] = 0;
         }
 
-        if (skb->len < tx_copybreak) {
-                used_bounce = 1;
-        } else {
-                data_dma_addr = dma_map_single(&adapter->vdev->dev, skb->data,
-                                               skb->len, DMA_TO_DEVICE);
-                if (dma_mapping_error(&adapter->vdev->dev, data_dma_addr)) {
-                        if (!firmware_has_feature(FW_FEATURE_CMO))
-                                ibmveth_error_printk("tx: unable to map "
-                                                     "xmit buffer\n");
-                        tx_map_failed++;
-                        used_bounce = 1;
-                }
-        }
+retry_bounce:
+        memset(descs, 0, sizeof(descs));
 
-        if (used_bounce) {
+        /*
+         * If a linear packet is below the rx threshold then
+         * copy it into the static bounce buffer. This avoids the
+         * cost of a TCE insert and remove.
+         */
+        if (force_bounce || (!skb_is_nonlinear(skb) &&
+                                (skb->len < tx_copybreak))) {
                 skb_copy_from_linear_data(skb, adapter->bounce_buffer,
                                           skb->len);
-                desc.fields.address = adapter->bounce_buffer_dma;
-        } else
-                desc.fields.address = data_dma_addr;
 
-        /* send the frame. Arbitrarily set retrycount to 1024 */
-        correlator = 0;
-        retry_count = 1024;
-        do {
-                lpar_rc = h_send_logical_lan(adapter->vdev->unit_address,
-                                             desc.desc, 0, 0, 0, 0, 0,
-                                             correlator, &correlator);
-        } while ((lpar_rc == H_BUSY) && (retry_count--));
-
-        if(lpar_rc != H_SUCCESS && lpar_rc != H_DROPPED) {
-                ibmveth_error_printk("tx: h_send_logical_lan failed with rc=%ld\n", lpar_rc);
-                ibmveth_error_printk("tx: valid=%d, len=%d, address=0x%08x\n",
-                                     (desc.fields.flags_len & IBMVETH_BUF_VALID) ? 1 : 0,
-                                     skb->len, desc.fields.address);
-                tx_send_failed++;
-                tx_dropped++;
+                descs[0].fields.flags_len = desc_flags | skb->len;
+                descs[0].fields.address = adapter->bounce_buffer_dma;
+
+                if (ibmveth_send(adapter, descs)) {
+                        adapter->tx_send_failed++;
+                        netdev->stats.tx_dropped++;
+                } else {
+                        netdev->stats.tx_packets++;
+                        netdev->stats.tx_bytes += skb->len;
+                }
+
+                goto out;
+        }
+
+        /* Map the header */
+        descs[0].fields.address = dma_map_single(&adapter->vdev->dev, skb->data,
+                                                 skb_headlen(skb),
+                                                 DMA_TO_DEVICE);
+        if (dma_mapping_error(&adapter->vdev->dev, descs[0].fields.address))
+                goto map_failed;
+
+        descs[0].fields.flags_len = desc_flags | skb_headlen(skb);
+
+        /* Map the frags */
+        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+                unsigned long dma_addr;
+                skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+                dma_addr = dma_map_page(&adapter->vdev->dev, frag->page,
+                                        frag->page_offset, frag->size,
+                                        DMA_TO_DEVICE);
+
+                if (dma_mapping_error(&adapter->vdev->dev, dma_addr))
+                        goto map_failed_frags;
+
+                descs[i+1].fields.flags_len = desc_flags | frag->size;
+                descs[i+1].fields.address = dma_addr;
+        }
+
+        if (ibmveth_send(adapter, descs)) {
+                adapter->tx_send_failed++;
+                netdev->stats.tx_dropped++;
         } else {
-                tx_packets++;
-                tx_bytes += skb->len;
+                netdev->stats.tx_packets++;
+                netdev->stats.tx_bytes += skb->len;
         }
 
-        if (!used_bounce)
-                dma_unmap_single(&adapter->vdev->dev, data_dma_addr,
-                                 skb->len, DMA_TO_DEVICE);
+        for (i = 0; i < skb_shinfo(skb)->nr_frags + 1; i++)
+                dma_unmap_page(&adapter->vdev->dev, descs[i].fields.address,
+                               descs[i].fields.flags_len & IBMVETH_BUF_LEN_MASK,
+                               DMA_TO_DEVICE);
 
 out:
-        netdev->stats.tx_dropped += tx_dropped;
-        netdev->stats.tx_bytes += tx_bytes;
-        netdev->stats.tx_packets += tx_packets;
-        adapter->tx_send_failed += tx_send_failed;
-        adapter->tx_map_failed += tx_map_failed;
-
         dev_kfree_skb(skb);
         return NETDEV_TX_OK;
+
+map_failed_frags:
+        last = i+1;
+        for (i = 0; i < last; i++)
+                dma_unmap_page(&adapter->vdev->dev, descs[i].fields.address,
+                               descs[i].fields.flags_len & IBMVETH_BUF_LEN_MASK,
+                               DMA_TO_DEVICE);
+
+map_failed:
+        if (!firmware_has_feature(FW_FEATURE_CMO))
+                ibmveth_error_printk("tx: unable to map xmit buffer\n");
+        adapter->tx_map_failed++;
+        skb_linearize(skb);
+        force_bounce = 1;
+        goto retry_bounce;
 }
 
 static int ibmveth_poll(struct napi_struct *napi, int budget)
@@ -1316,6 +1379,7 @@ static int __devinit ibmveth_probe(struct vio_dev *dev, const struct vio_device_
         netdev->netdev_ops = &ibmveth_netdev_ops;
         netdev->ethtool_ops = &netdev_ethtool_ops;
         SET_NETDEV_DEV(netdev, &dev->dev);
+        netdev->features |= NETIF_F_SG;
 
         memcpy(netdev->dev_addr, &adapter->mac_addr, netdev->addr_len);