【OVS2.5.0源码分析】datapath之netlink

ovs datapath是通过netlink与用户态进行通信的，实现dp、端口、流表、packet的操作。 netlink的注册是在datapath模块的初始化函数中实现的。

1、dp_init函数

static int __init dp_init(void)
{
int err;

BUILD_BUG_ON(sizeof(struct ovs_skb_cb) > FIELD_SIZEOF(struct sk_buff, cb));

pr_info("Open vSwitch switching datapath %s\n", VERSION);

err = compat_init();
if (err)
goto error;

err = action_fifos_init();
if (err)
goto error_compat_exit;

err = ovs_internal_dev_rtnl_link_register();
if (err)
goto error_action_fifos_exit;

err = ovs_flow_init();
if (err)
goto error_unreg_rtnl_link;

err = ovs_vport_init();
if (err)
goto error_flow_exit;

err = register_pernet_device(&ovs_net_ops);
if (err)
goto error_vport_exit;

err = register_netdevice_notifier(&ovs_dp_device_notifier);
if (err)
goto error_netns_exit;

err = ovs_netdev_init();
if (err)
goto error_unreg_notifier;

err = dp_register_genl(); //注册netlink处理函数
if (err < 0)
goto error_unreg_netdev;

return 0;

error_unreg_netdev:
ovs_netdev_exit();
error_unreg_notifier:
unregister_netdevice_notifier(&ovs_dp_device_notifier);
error_netns_exit:
unregister_pernet_device(&ovs_net_ops);
error_vport_exit:
ovs_vport_exit();
error_flow_exit:
ovs_flow_exit();
error_unreg_rtnl_link:
ovs_internal_dev_rtnl_link_unregister();
error_action_fifos_exit:
action_fifos_exit();
error_compat_exit:
compat_exit();
error:
return err;
}

2、genl_register_family函数

#define genl_register_family rpl_genl_register_family
static inline int rpl_genl_register_family(struct genl_family *family)
{
family->module = THIS_MODULE;
return rpl___genl_register_family(family); //注册netlink
}3、rpl___genl_register_family函数
int rpl___genl_register_family(struct rpl_genl_family *f)
{
int err;

f->comp
4000
at_family.id = f->id;
f->compat_family.hdrsize = f->hdrsize;
strncpy(f->compat_family.name, f->name, GENL_NAMSIZ);
f->compat_family.version = f->version;
f->compat_family.maxattr = f->maxattr;
f->compat_family.netnsok = f->netnsok;
#ifdef HAVE_PARALLEL_OPS
f->compat_family.parallel_ops = f->parallel_ops;
#endif
err = genl_register_family_with_ops(&f->compat_family, //调用系统接口，可以不用关注消息处理，可以把ops作为netlink的处理入口函数
(struct genl_ops *) f->ops, f->n_ops);
if (err)
goto error;

if (f->mcgrps) {
/* Need to Fix GROUP_ID() for more than one group. */
BUG_ON(f->n_mcgrps > 1);
err = genl_register_mc_group(&f->compat_family, //调用系统接口，暂时只看到dp中用ovs_notify中在使用，没想明白，估计要深入netlink实现才能搞清楚
(struct genl_multicast_group *) f->mcgrps);
if (err)
goto error;
}
error:
return err;

}netlink的操作是由dp_genl_families定义的，一共有4类。

static struct genl_family *dp_genl_families[] = {
&dp_datapath_genl_family,
&dp_vport_genl_family,
&dp_flow_genl_family,
&dp_packet_genl_family,
};

datapath netlink定义：
static struct genl_family dp_datapath_genl_family = {
.id = GENL_ID_GENERATE,
.hdrsize = sizeof(struct ovs_header),
.name = OVS_DATAPATH_FAMILY,
.version = OVS_DATAPATH_VERSION,
.maxattr = OVS_DP_ATTR_MAX,
.netnsok = true,
.parallel_ops = true,
.ops = dp_datapath_genl_ops,
.n_ops = ARRAY_SIZE(dp_datapath_genl_ops),
.mcgrps = &ovs_dp_datapath_multicast_group,
.n_mcgrps = 1,
};

static struct genl_ops dp_datapath_genl_ops[] = {
{ .cmd = OVS_DP_CMD_NEW,
.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */
.policy = datapath_policy,
.doit = ovs_dp_cmd_new //创建datapath
},
{ .cmd = OVS_DP_CMD_DEL,
.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */
.policy = datapath_policy,
.doit = ovs_dp_cmd_del //删除datapath
},
{ .cmd = OVS_DP_CMD_GET,
.flags = 0, /* OK for unprivileged users. */
.policy = datapath_policy,
.doit = ovs_dp_cmd_get,
.dumpit = ovs_dp_cmd_dump //导出datapath
},
{ .cmd = OVS_DP_CMD_SET,
.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */
.policy = datapath_policy,
.doit = ovs_dp_cmd_set, //修改datapath
},
};
vport netlink定义：
struct genl_family dp_vport_genl_family = {
.id = GENL_ID_GENERATE,
.hdrsize = sizeof(struct ovs_header),
.name = OVS_VPORT_FAMILY,
.version = OVS_VPORT_VERSION,
.maxattr = OVS_VPORT_ATTR_MAX,
.netnsok = true,
.parallel_ops = true,
.ops = dp_vport_genl_ops,
.n_ops = ARRAY_SIZE(dp_vport_genl_ops),
.mcgrps = &ovs_dp_vport_multicast_group,
.n_mcgrps = 1,
};

static struct genl_ops dp_vport_genl_ops[] = {
{ .cmd = OVS_VPORT_CMD_NEW,
.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */
.policy = vport_policy,
.doit = ovs_vport_cmd_new //创建vport
},
{ .cmd = OVS_VPORT_CMD_DEL,
.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */
.policy = vport_policy,
.doit = ovs_vport_cmd_del //删除vport
},
{ .cmd = OVS_VPORT_CMD_GET,
.flags = 0, /* OK for unprivileged users. */
.policy = vport_policy,
.doit = ovs_vport_cmd_get,
.dumpit = ovs_vport_cmd_dump //导出vport
},
{ .cmd = OVS_VPORT_CMD_SET,
.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */
.policy = vport_policy,
.doit = ovs_vport_cmd_set, //修改vport
},
};
精确流表 netlink定义：
static struct genl_family dp_flow_genl_family = {
.id = GENL_ID_GENERATE,
.hdrsize = sizeof(struct ovs_header),
.name = OVS_FLOW_FAMILY,
.version = OVS_FLOW_VERSION,
.maxattr = OVS_FLOW_ATTR_MAX,
.netnsok = true,
.parallel_ops = true,
.ops = dp_flow_genl_ops,
.n_ops = ARRAY_SIZE(dp_flow_genl_ops),
.mcgrps = &ovs_dp_flow_multicast_group,
.n_mcgrps = 1,
};

static struct genl_ops dp_flow_genl_ops[] = {
{ .cmd = OVS_FLOW_CMD_NEW,
.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */
.policy = flow_policy,
.doit = ovs_flow_cmd_new //添加精确流表
},
{ .cmd = OVS_FLOW_CMD_DEL,
.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */
.policy = flow_policy,
.doit = ovs_flow_cmd_del //删除精确流表
},
{ .cmd = OVS_FLOW_CMD_GET,
.flags = 0, /* OK for unprivileged users. */
.policy = flow_policy,
.doit = ovs_flow_cmd_get,
.dumpit = ovs_flow_cmd_dump //导出精确流表
},
{ .cmd = OVS_FLOW_CMD_SET,
.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */
.policy = flow_policy,
.doit = ovs_flow_cmd_set, //修改精确流表
},
};packet netlink定义：
static struct genl_family dp_packet_genl_family = {
.id = GENL_ID_GENERATE,
.hdrsize = sizeof(struct ovs_header),
.name = OVS_PACKET_FAMILY,
.version = OVS_PACKET_VERSION,
.maxattr = OVS_PACKET_ATTR_MAX,
.netnsok = true,
.parallel_ops = true,
.ops = dp_packet_genl_ops,
.n_ops = ARRAY_SIZE(dp_packet_genl_ops),
};

static struct genl_ops dp_packet_genl_ops[] = {
{ .cmd = OVS_PACKET_CMD_EXECUTE,
.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */
.policy = packet_policy,
.doit = ovs_packet_cmd_execute //执行报文action操作
}
};