netdevsim: allow two netdevsim ports to be connected

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@davidwei.uk>
Reviewed-by: Maciek Machnikowski <maciek@machnikowski.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/netdevsim/bus.c b/drivers/net/netdevsim/bus.c
index 0c5aff6..64c0cdd 100644 (file)
--- 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 77e8250..9063f4f 100644 (file)
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -413,8 +413,13 @@ err_free_netdev:
 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 028c825..c8b45b0 100644 (file)
--- 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);