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Date: Wed, 1 Jun 2016 14:15:54 -0700
From: Stefan Hajnoczi <stefanha@...hat.com>
To: ggarcia@...a.uab.cat
Cc: netdev@...r.kernel.org, jhansen@...are.com
Subject: Re: [RFC 2/3] vsockmon: Add vsockmon device
On Sat, May 28, 2016 at 06:29:06PM +0200, ggarcia@...a.uab.cat wrote:
> From: Gerard Garcia <ggarcia@...c.uab.cat>
>
> Signed-off-by: Gerard Garcia <ggarcia@...c.uab.cat>
> ---
> drivers/net/Kconfig | 8 ++
> drivers/net/Makefile | 1 +
> drivers/net/vsockmon.c | 171 ++++++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/Kbuild | 1 +
> include/uapi/linux/vsockmon.h | 37 +++++++++
> 5 files changed, 218 insertions(+)
> create mode 100644 drivers/net/vsockmon.c
> create mode 100644 include/uapi/linux/vsockmon.h
>
> diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
> index 0c5415b..42c43b6 100644
> --- a/drivers/net/Kconfig
> +++ b/drivers/net/Kconfig
> @@ -330,6 +330,14 @@ config NET_VRF
> This option enables the support for mapping interfaces into VRF's. The
> support enables VRF devices.
>
> +config VSOCKMON
> + tristate "Virtual vsock monitoring device"
> + depends on VHOST_VSOCK
> + ---help---
> + This option enables a monitoring net device for vsock sockets. It is
> + mostly intended for developers or support to debug vsock issues. If
> + unsure, say N.
> +
> endif # NET_CORE
>
> config SUNGEM_PHY
> diff --git a/drivers/net/Makefile b/drivers/net/Makefile
> index 7336cbd..e2188d4 100644
> --- a/drivers/net/Makefile
> +++ b/drivers/net/Makefile
> @@ -28,6 +28,7 @@ obj-$(CONFIG_GENEVE) += geneve.o
> obj-$(CONFIG_GTP) += gtp.o
> obj-$(CONFIG_NLMON) += nlmon.o
> obj-$(CONFIG_NET_VRF) += vrf.o
> +obj-$(CONFIG_VSOCKMON) += vsockmon.o
>
> #
> # Networking Drivers
> diff --git a/drivers/net/vsockmon.c b/drivers/net/vsockmon.c
> new file mode 100644
> index 0000000..becddc9
> --- /dev/null
> +++ b/drivers/net/vsockmon.c
> @@ -0,0 +1,171 @@
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/if_arp.h>
> +#include <net/rtnetlink.h>
> +#include <net/sock.h>
> +#include <net/af_vsock.h>
> +#include <uapi/linux/vsockmon.h>
> +
> +/* Virtio transport max packet size plus header */
> +#define DEFAULT_MTU 1024 * 64 + sizeof(struct af_vsockmon_hdr);
> +
> +struct pcpu_lstats {
> + u64 rx_packets;
> + u64 rx_bytes;
> + struct u64_stats_sync syncp;
> +};
> +
> +static int vsockmon_dev_init(struct net_device *dev)
> +{
> + dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
> + return dev->lstats == NULL ? -ENOMEM : 0;
> +}
> +
> +static void vsockmon_dev_uninit(struct net_device *dev)
> +{
> + free_percpu(dev->lstats);
> +}
> +
> +struct vsockmon {
> + struct vsock_tap vt;
> +};
> +
> +static int vsockmon_open(struct net_device *dev)
> +{
> + struct vsockmon *vsockmon = netdev_priv(dev);
> +
> + vsockmon->vt.dev = dev;
> + vsockmon->vt.module = THIS_MODULE;
> + return vsock_add_tap(&vsockmon->vt);
> +}
> +
> +static int vsockmon_close(struct net_device *dev) {
> + struct vsockmon *vsockmon = netdev_priv(dev);
> +
> + return vsock_remove_tap(&vsockmon->vt);
> +}
> +
> +static netdev_tx_t vsockmon_xmit(struct sk_buff *skb, struct net_device *dev)
> +{
> + int len = skb->len;
> + struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
> +
> + u64_stats_update_begin(&stats->syncp);
> + stats->rx_bytes += len;
> + stats->rx_packets++;
> + u64_stats_update_end(&stats->syncp);
> +
> + dev_kfree_skb(skb);
> +
> + return NETDEV_TX_OK;
> +}
> +
> +static struct rtnl_link_stats64 *
> +vsockmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
> +{
> + int i;
> + u64 bytes = 0, packets = 0;
> +
> + for_each_possible_cpu(i) {
> + const struct pcpu_lstats *vstats;
> + u64 tbytes, tpackets;
> + unsigned int start;
> +
> + vstats = per_cpu_ptr(dev->lstats, i);
> +
> + do {
> + start = u64_stats_fetch_begin_irq(&vstats->syncp);
> + tbytes = vstats->rx_bytes;
> + tpackets = vstats->rx_packets;
> + } while (u64_stats_fetch_retry_irq(&vstats->syncp, start));
> +
> + packets += tpackets;
> + bytes += tbytes;
> + }
> +
> + stats->rx_packets = packets;
> + stats->tx_packets = 0;
> +
> + stats->rx_bytes = bytes;
> + stats->tx_bytes = 0;
> +
> + return stats;
> +}
> +
> +static int vsockmon_is_valid_mtu(int new_mtu)
> +{
> + return new_mtu >= (int) sizeof(struct af_vsockmon_hdr);
> +}
> +
> +static int vsockmon_change_mtu(struct net_device *dev, int new_mtu)
> +{
> + if (!vsockmon_is_valid_mtu(new_mtu))
> + return -EINVAL;
> +
> + dev->mtu = new_mtu;
> + return 0;
> +}
I wonder if the mtu serves any purpose. What happens when you change it
from the default value?
> +
> +static const struct net_device_ops vsockmon_ops = {
> + .ndo_init = vsockmon_dev_init,
> + .ndo_uninit = vsockmon_dev_uninit,
> + .ndo_open = vsockmon_open,
> + .ndo_stop = vsockmon_close,
> + .ndo_start_xmit = vsockmon_xmit,
> + .ndo_get_stats64 = vsockmon_get_stats64,
> + .ndo_change_mtu = vsockmon_change_mtu,
> +};
> +
> +static u32 always_on(struct net_device *dev)
> +{
> + return 1;
> +}
> +
> +static const struct ethtool_ops vsockmon_ethtool_ops = {
> + .get_link = always_on,
> +};
> +
> +static void vsockmon_setup(struct net_device *dev)
> +{
> + dev->type = ARPHRD_VSOCKMON;
> + dev->priv_flags |= IFF_NO_QUEUE;
> +
> + dev->netdev_ops = &vsockmon_ops;
> + dev->ethtool_ops = &vsockmon_ethtool_ops;
> + dev->destructor = free_netdev;
> +
> + dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
> + NETIF_F_HIGHDMA | NETIF_F_LLTX;
> +
> + dev->flags = IFF_NOARP;
> +
> + dev->mtu = DEFAULT_MTU;
> +}
> +
> +static struct rtnl_link_ops vsockmon_link_ops __read_mostly = {
> + .kind = "vsockmon",
> + .priv_size = sizeof(struct vsockmon),
> + .setup = vsockmon_setup,
> +};
> +
> +static __init int vsockmon_register(void)
> +{
> + int ret = rtnl_link_register(&vsockmon_link_ops);
> + if (!ret)
> + vsock_init_tap();
> +
> + return ret;
> +}
> +
> +static __exit void vsockmon_unregister(void)
> +{
> + rtnl_link_unregister(&vsockmon_link_ops);
> +}
> +
> +module_init(vsockmon_register);
> +module_exit(vsockmon_unregister);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Gerard Garcia <ggarcia@...c.uab.cat>");
> +MODULE_DESCRIPTION("Vsock monitoring device");
> +MODULE_ALIAS_RTNL_LINK("vsockmon");
there should be some mention that this is derived from nlmon.c.
> diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
> index 5f047d2..b1836cc 100644
> --- a/include/uapi/linux/Kbuild
> +++ b/include/uapi/linux/Kbuild
> @@ -454,6 +454,7 @@ header-y += virtio_scsi.h
> header-y += virtio_types.h
> header-y += virtio_vsock.h
> header-y += vm_sockets.h
> +header-y += vsockmon.h
> header-y += vt.h
> header-y += wait.h
> header-y += wanrouter.h
> diff --git a/include/uapi/linux/vsockmon.h b/include/uapi/linux/vsockmon.h
> new file mode 100644
> index 0000000..c73166f
> --- /dev/null
> +++ b/include/uapi/linux/vsockmon.h
> @@ -0,0 +1,37 @@
> +#ifndef _UAPI_VSOCKMON_H
> +#define _UAPI_VSOCKMON_H
> +
> +#include <linux/virtio_vsock.h>
> +
> +/* Packet structure of packets received from the vsockmon device. */
> +
> +struct af_vsockmon_g {
> + unsigned short op; /* enum af_vsock_g_ops */
> + unsigned int src_cid;
> + unsigned int src_port;
> + unsigned int dst_cid;
> + unsigned int dst_port;
> +};
> +
> +struct af_vsockmon_hdr {
> + unsigned short type; /* enum af_vosck_type */
> + struct af_vsockmon_g g_hdr;
> + union {
> + struct virtio_vsock_hdr virtio_hdr;
> + } t_hdr;
> +};
How does endianness work? virtio_hdr uses little-endian fields on the
wire. I guess that af_vsockmon_g is always CPU-endian.
> +
> +enum af_vsockmon_type {
> + AF_VSOCK_GENERIC = 1, /* No transport header */
> + AF_VSOCK_VIRTIO = 2, /* Addtional virtio transport header */
> +};
> +
> +enum af_vsockmon_g_ops {
> + AF_VSOCK_G_OP_UNKNOWN = 0,
> + AF_VSOCK_G_OP_CONNECT = 1,
> + AF_VSOCK_G_OP_DISCONNECT = 2,
> + AF_VSOCK_G_OP_CONTROL = 3,
> + AF_VSOCK_G_OP_PAYLOAD = 4,
> +};
> +
> +#endif
> --
> 2.8.3
>
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