virtio_net: use virtqueue_add_sgs[] for command buffers.

It's a bit cleaner to hand multiple sgs, rather than one big one.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Tested-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 57ac4b0..be70487 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -39,7 +39,6 @@ module_param(gso, bool, 0444);
 #define MAX_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)
 #define GOOD_COPY_LEN  128
 
-#define VIRTNET_SEND_COMMAND_SG_MAX    2
 #define VIRTNET_DRIVER_VERSION "1.0.0"
 
 struct virtnet_stats {
@@ -767,32 +766,35 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
  * never fail unless improperly formated.
  */
 static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
-                                struct scatterlist *data, int out, int in)
+                                struct scatterlist *out,
+                                struct scatterlist *in)
 {
-       struct scatterlist *s, sg[VIRTNET_SEND_COMMAND_SG_MAX + 2];
+       struct scatterlist *sgs[4], hdr, stat;
        struct virtio_net_ctrl_hdr ctrl;
        virtio_net_ctrl_ack status = ~0;
-       unsigned int tmp;
-       int i;
+       unsigned out_num = 0, in_num = 0, tmp;
 
        /* Caller should know better */
-       BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ) ||
-               (out + in > VIRTNET_SEND_COMMAND_SG_MAX));
-
-       out++; /* Add header */
-       in++; /* Add return status */
+       BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));
 
        ctrl.class = class;
        ctrl.cmd = cmd;
+       /* Add header */
+       sg_init_one(&hdr, &ctrl, sizeof(ctrl));
+       sgs[out_num++] = &hdr;
 
-       sg_init_table(sg, out + in);
+       if (out)
+               sgs[out_num++] = out;
+       if (in)
+               sgs[out_num + in_num++] = in;
 
-       sg_set_buf(&sg[0], &ctrl, sizeof(ctrl));
-       for_each_sg(data, s, out + in - 2, i)
-               sg_set_buf(&sg[i + 1], sg_virt(s), s->length);
-       sg_set_buf(&sg[out + in - 1], &status, sizeof(status));
+       /* Add return status. */
+       sg_init_one(&stat, &status, sizeof(status));
+       sgs[out_num + in_num++] = &stat;
 
-       BUG_ON(virtqueue_add_buf(vi->cvq, sg, out, in, vi, GFP_ATOMIC) < 0);
+       BUG_ON(out_num + in_num > ARRAY_SIZE(sgs));
+       BUG_ON(virtqueue_add_sgs(vi->cvq, sgs, out_num, in_num, vi, GFP_ATOMIC)
+              < 0);
 
        virtqueue_kick(vi->cvq);
 
@@ -821,7 +823,7 @@ static int virtnet_set_mac_address(struct net_device *dev, void *p)
                sg_init_one(&sg, addr->sa_data, dev->addr_len);
                if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
                                          VIRTIO_NET_CTRL_MAC_ADDR_SET,
-                                         &sg, 1, 0)) {
+                                         &sg, NULL)) {
                        dev_warn(&vdev->dev,
                                 "Failed to set mac address by vq command.\n");
                        return -EINVAL;
@@ -889,8 +891,7 @@ static void virtnet_ack_link_announce(struct virtnet_info *vi)
 {
        rtnl_lock();
        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_ANNOUNCE,
-                                 VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL,
-                                 0, 0))
+                                 VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL, NULL))
                dev_warn(&vi->dev->dev, "Failed to ack link announce.\n");
        rtnl_unlock();
 }
@@ -908,7 +909,7 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs)
        sg_init_one(&sg, &s, sizeof(s));
 
        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MQ,
-                                 VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET, &sg, 1, 0)){
+                                 VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET, &sg, NULL)) {
                dev_warn(&dev->dev, "Fail to set num of queue pairs to %d\n",
                         queue_pairs);
                return -EINVAL;
@@ -955,7 +956,7 @@ static void virtnet_set_rx_mode(struct net_device *dev)
 
        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
                                  VIRTIO_NET_CTRL_RX_PROMISC,
-                                 sg, 1, 0))
+                                 sg, NULL))
                dev_warn(&dev->dev, "Failed to %sable promisc mode.\n",
                         promisc ? "en" : "dis");
 
@@ -963,7 +964,7 @@ static void virtnet_set_rx_mode(struct net_device *dev)
 
        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
                                  VIRTIO_NET_CTRL_RX_ALLMULTI,
-                                 sg, 1, 0))
+                                 sg, NULL))
                dev_warn(&dev->dev, "Failed to %sable allmulti mode.\n",
                         allmulti ? "en" : "dis");
 
@@ -1000,7 +1001,7 @@ static void virtnet_set_rx_mode(struct net_device *dev)
 
        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
                                  VIRTIO_NET_CTRL_MAC_TABLE_SET,
-                                 sg, 2, 0))
+                                 sg, NULL))
                dev_warn(&dev->dev, "Failed to set MAC fitler table.\n");
 
        kfree(buf);
@@ -1014,7 +1015,7 @@ static int virtnet_vlan_rx_add_vid(struct net_device *dev, u16 vid)
        sg_init_one(&sg, &vid, sizeof(vid));
 
        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
-                                 VIRTIO_NET_CTRL_VLAN_ADD, &sg, 1, 0))
+                                 VIRTIO_NET_CTRL_VLAN_ADD, &sg, NULL))
                dev_warn(&dev->dev, "Failed to add VLAN ID %d.\n", vid);
        return 0;
 }
@@ -1027,7 +1028,7 @@ static int virtnet_vlan_rx_kill_vid(struct net_device *dev, u16 vid)
        sg_init_one(&sg, &vid, sizeof(vid));
 
        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
-                                 VIRTIO_NET_CTRL_VLAN_DEL, &sg, 1, 0))
+                                 VIRTIO_NET_CTRL_VLAN_DEL, &sg, NULL))
                dev_warn(&dev->dev, "Failed to kill VLAN ID %d.\n", vid);
        return 0;
 }