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Message-ID: <ac3d9c05-402f-435c-a5d2-29ab4f274bf5@machnikowski.net>
Date: Thu, 29 Feb 2024 18:11:53 +0100
From: Maciek Machnikowski <maciek@...hnikowski.net>
To: David Wei <dw@...idwei.uk>, Jakub Kicinski <kuba@...nel.org>,
Jiri Pirko <jiri@...nulli.us>, Sabrina Dubroca <sd@...asysnail.net>,
horms@...nel.org, netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH v14 1/5] netdevsim: allow two netdevsim ports to be
connected
On 29/02/2024 00:22, David Wei wrote:
> Add two netdevsim bus attribute to sysfs:
> /sys/bus/netdevsim/link_device
> /sys/bus/netdevsim/unlink_device
>
> Writing "A M B N" to link_device will link netdevsim M in netnsid A with
> netdevsim N in netnsid B.
>
> Writing "A M" to unlink_device will unlink netdevsim M in netnsid A from
> its peer, if any.
>
> rtnl_lock is taken to ensure nothing changes during the linking.
>
> Signed-off-by: David Wei <dw@...idwei.uk>
> ---
> drivers/net/netdevsim/bus.c | 145 ++++++++++++++++++++++++++++++
> drivers/net/netdevsim/netdev.c | 10 +++
> drivers/net/netdevsim/netdevsim.h | 2 +
> 3 files changed, 157 insertions(+)
>
> diff --git a/drivers/net/netdevsim/bus.c b/drivers/net/netdevsim/bus.c
> index 0c5aff63d242..64c0cdd31bf8 100644
> --- a/drivers/net/netdevsim/bus.c
> +++ b/drivers/net/netdevsim/bus.c
> @@ -232,9 +232,154 @@ del_device_store(const struct bus_type *bus, const char *buf, size_t count)
> }
> static BUS_ATTR_WO(del_device);
>
> +static ssize_t link_device_store(const struct bus_type *bus, const char *buf, size_t count)
> +{
> + struct netdevsim *nsim_a, *nsim_b, *peer;
> + struct net_device *dev_a, *dev_b;
> + unsigned int ifidx_a, ifidx_b;
> + int netnsfd_a, netnsfd_b, err;
> + struct net *ns_a, *ns_b;
> +
> + err = sscanf(buf, "%d:%u %d:%u", &netnsfd_a, &ifidx_a, &netnsfd_b,
> + &ifidx_b);
> + if (err != 4) {
> + pr_err("Format for linking two devices is \"netnsfd_a:ifidx_a netnsfd_b:ifidx_b\" (int uint int uint).\n");
> + return -EINVAL;
> + }
> +
> + ns_a = get_net_ns_by_fd(netnsfd_a);
> + if (IS_ERR(ns_a)) {
> + pr_err("Could not find netns with fd: %d\n", netnsfd_a);
> + return -EINVAL;
> + }
> +
> + ns_b = get_net_ns_by_fd(netnsfd_b);
> + if (IS_ERR(ns_b)) {
> + pr_err("Could not find netns with fd: %d\n", netnsfd_b);
> + put_net(ns_a);
> + return -EINVAL;
> + }
> +
> + err = -EINVAL;
> + rtnl_lock();
> + dev_a = __dev_get_by_index(ns_a, ifidx_a);
> + if (!dev_a) {
> + pr_err("Could not find device with ifindex %u in netnsfd %d\n",
> + ifidx_a, netnsfd_a);
> + goto out_err;
> + }
> +
> + if (!netdev_is_nsim(dev_a)) {
> + pr_err("Device with ifindex %u in netnsfd %d is not a netdevsim\n",
> + ifidx_a, netnsfd_a);
> + goto out_err;
> + }
> +
> + dev_b = __dev_get_by_index(ns_b, ifidx_b);
> + if (!dev_b) {
> + pr_err("Could not find device with ifindex %u in netnsfd %d\n",
> + ifidx_b, netnsfd_b);
> + goto out_err;
> + }
> +
> + if (!netdev_is_nsim(dev_b)) {
> + pr_err("Device with ifindex %u in netnsfd %d is not a netdevsim\n",
> + ifidx_b, netnsfd_b);
> + goto out_err;
> + }
> +
> + if (dev_a == dev_b) {
> + pr_err("Cannot link a netdevsim to itself\n");
> + goto out_err;
> + }
> +
> + err = -EBUSY;
> + nsim_a = netdev_priv(dev_a);
> + peer = rtnl_dereference(nsim_a->peer);
> + if (peer) {
> + pr_err("Netdevsim %d:%u is already linked\n", netnsfd_a,
> + ifidx_a);
> + goto out_err;
> + }
> +
> + nsim_b = netdev_priv(dev_b);
> + peer = rtnl_dereference(nsim_b->peer);
> + if (peer) {
> + pr_err("Netdevsim %d:%u is already linked\n", netnsfd_b,
> + ifidx_b);
> + goto out_err;
> + }
> +
> + err = 0;
> + rcu_assign_pointer(nsim_a->peer, nsim_b);
> + rcu_assign_pointer(nsim_b->peer, nsim_a);
> +
> +out_err:
> + put_net(ns_b);
> + put_net(ns_a);
> + rtnl_unlock();
> +
> + return !err ? count : err;
> +}
> +static BUS_ATTR_WO(link_device);
> +
> +static ssize_t unlink_device_store(const struct bus_type *bus, const char *buf, size_t count)
> +{
> + struct netdevsim *nsim, *peer;
> + struct net_device *dev;
> + unsigned int ifidx;
> + int netnsfd, err;
> + struct net *ns;
> +
> + err = sscanf(buf, "%u:%u", &netnsfd, &ifidx);
> + if (err != 2) {
> + pr_err("Format for unlinking a device is \"netnsfd:ifidx\" (int uint).\n");
> + return -EINVAL;
> + }
> +
> + ns = get_net_ns_by_fd(netnsfd);
> + if (IS_ERR(ns)) {
> + pr_err("Could not find netns with fd: %d\n", netnsfd);
> + return -EINVAL;
> + }
> +
> + err = -EINVAL;
> + rtnl_lock();
> + dev = __dev_get_by_index(ns, ifidx);
> + if (!dev) {
> + pr_err("Could not find device with ifindex %u in netnsfd %d\n",
> + ifidx, netnsfd);
> + goto out_put_netns;
> + }
> +
> + if (!netdev_is_nsim(dev)) {
> + pr_err("Device with ifindex %u in netnsfd %d is not a netdevsim\n",
> + ifidx, netnsfd);
> + goto out_put_netns;
> + }
> +
> + nsim = netdev_priv(dev);
> + peer = rtnl_dereference(nsim->peer);
> + if (!peer)
> + goto out_put_netns;
> +
> + err = 0;
> + RCU_INIT_POINTER(nsim->peer, NULL);
> + RCU_INIT_POINTER(peer->peer, NULL);
> +
> +out_put_netns:
> + put_net(ns);
> + rtnl_unlock();
> +
> + return !err ? count : err;
> +}
> +static BUS_ATTR_WO(unlink_device);
> +
> static struct attribute *nsim_bus_attrs[] = {
> &bus_attr_new_device.attr,
> &bus_attr_del_device.attr,
> + &bus_attr_link_device.attr,
> + &bus_attr_unlink_device.attr,
> NULL
> };
> ATTRIBUTE_GROUPS(nsim_bus);
> diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
> index 77e8250282a5..9063f4f2971b 100644
> --- a/drivers/net/netdevsim/netdev.c
> +++ b/drivers/net/netdevsim/netdev.c
> @@ -413,8 +413,13 @@ nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port)
> void nsim_destroy(struct netdevsim *ns)
> {
> struct net_device *dev = ns->netdev;
> + struct netdevsim *peer;
>
> rtnl_lock();
> + peer = rtnl_dereference(ns->peer);
> + if (peer)
> + RCU_INIT_POINTER(peer->peer, NULL);
> + RCU_INIT_POINTER(ns->peer, NULL);
> unregister_netdevice(dev);
> if (nsim_dev_port_is_pf(ns->nsim_dev_port)) {
> nsim_macsec_teardown(ns);
> @@ -427,6 +432,11 @@ void nsim_destroy(struct netdevsim *ns)
> free_netdev(dev);
> }
>
> +bool netdev_is_nsim(struct net_device *dev)
> +{
> + return dev->netdev_ops == &nsim_netdev_ops;
> +}
> +
> static int nsim_validate(struct nlattr *tb[], struct nlattr *data[],
> struct netlink_ext_ack *extack)
> {
> diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
> index 028c825b86db..c8b45b0d955e 100644
> --- a/drivers/net/netdevsim/netdevsim.h
> +++ b/drivers/net/netdevsim/netdevsim.h
> @@ -125,11 +125,13 @@ struct netdevsim {
> } udp_ports;
>
> struct nsim_ethtool ethtool;
> + struct netdevsim __rcu *peer;
> };
>
> struct netdevsim *
> nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port);
> void nsim_destroy(struct netdevsim *ns);
> +bool netdev_is_nsim(struct net_device *dev);
>
> void nsim_ethtool_init(struct netdevsim *ns);
>
Reviewed-by: Maciek Machnikowski <maciek@...hnikowski.net>
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