???????????linux kernel 2.6.32??bridge??????????????????linux kernel 3.10??bridge????????????????CentOS 5??CentOS 7?????????3.10 kernel??bridge????????????????vlan??????????brdige???????????á?
????1. netdev_rx_handler_register
????????????????????????????????netdev_rx_handler_register???????????2.6???????е??
????netdev_rx_handler_register
/*
* dev: ????????????dev
* rx_handler: ???????????
* rx_handler_data: ???rx_handler_data????????
*/
int netdev_rx_handler_register(struct net_device *dev??
rx_handler_func_t *rx_handler??
void *rx_handler_data)
{
ASSERT_RTNL();
if (dev->rx_handler)
return -EBUSY;
/* Note: rx_handler_data must be set before rx_handler */
rcu_assign_pointer(dev->rx_handler_data?? rx_handler_data);
rcu_assign_pointer(dev->rx_handler?? rx_handler);
return 0;
}
?????????????????豸??net_device??????????????????__netif_receive_skb?????и??????skb???豸????????????????????????????????????μ??????br_handle_frame???????bonding??????bond_handle_frame??????????????????????????????????????????????????????????????????????3.10?е?openvswitch??OpenvSwitch??3.10?????????????????netdev vport?????netdev_create??
????netdev_create
????static struct vport *netdev_create(const struct vport_parms *parms)
????{
????struct vport *vport;
????/....../
????err = netdev_rx_handler_register(netdev_vport->dev?? netdev_frame_hook??vport);
????/....../
????}
????????????????netdev vport????豸?????????????netdev_frame_hook???????????????openvswitch???????????????OpenvSwitch??????????????????2.6???????????滻??bridge??br_handle_frame_hook???????????bridge???????OpenvSwitch?????
????2. Bridge??????????
???????????netif_receive_skb????????????????????????Э?????????
????netif_receive_skb
int netif_receive_skb(struct sk_buff *skb)
{
int ret;
if (skb_defer_rx_timestamp(skb))
return NET_RX_SUCCESS;
rcu_read_lock();
/*RPS??????????????????????RPS????? ??????????????cpu?????????н??и????????*/
#ifdef CONFIG_RPS
if (static_key_false(&rps_needed)) {
struct rps_dev_flow voidflow?? *rflow = &voidflow;
int cpu = get_rps_cpu(skb->dev?? skb?? &rflow);
if (cpu >= 0) {
ret = enqueue_to_backlog(skb?? cpu?? &rflow->last_qtail);
rcu_read_unlock();
return ret;
}
}
#endif
ret = __netif_receive_skb(skb);
rcu_read_unlock();
return ret;
}
????netif_receive_skb???????????????RPS????????????__netif_receive_skb??
????__netif_receive_skb????????????????????????????? __netif_receive_skb_core???????????????????2.6????netif_receive_skb?????′?????????bridge?????????
????__netif_receive_skb_core
static int __netif_receive_skb_core(struct sk_buff *skb?? bool pfmemalloc)
{
struct packet_type *ptype?? *pt_prev;
rx_handler_func_t *rx_handler;
struct net_device *orig_dev;
struct net_device *null_or_dev;
bool deliver_exact = false;
int ret = NET_RX_DROP;
__be16 type;
/*......*/
orig_dev = skb->dev;
skb_reset_network_header(skb);
pt_prev = NULL;
skb->skb_iif = skb->dev->ifindex;
/*ptype_allЭ?鴦???tcpdump?????????*/
list_for_each_entry_rcu(ptype?? &ptype_all?? list) {
if (!ptype->dev || ptype->dev == skb->dev) {
if (pt_prev)
ret = deliver_skb(skb?? pt_prev?? orig_dev);
pt_prev = ptype;
}
}
/*???y????豸??rx_handler*/
rx_handler = rcu_dereference(skb->dev->rx_handler);
if (rx_handler) {
if (pt_prev) {
ret = deliver_skb(skb?? pt_prev?? orig_dev);
pt_prev = NULL;
}
switch (rx_handler(&skb)) {
case RX_HANDLER_CONSUMED:
ret = NET_RX_SUCCESS;
goto out;
case RX_HANDLER_ANOTHER:
goto another_round;
case RX_HANDLER_EXACT:
deliver_exact = true;
case RX_HANDLER_PASS:
break;
default:
BUG();
}
}
/*???? skb->protocol????????Э??*/
type = skb->protocol;
list_for_each_entry_rcu(ptype??&ptype_base[ntohs(type) & PTYPE_HASH_MASK]?? list) {
if (ptype->type == type && (ptype->dev == null_or_dev || ptype->dev == skb->dev ||ptype->dev == orig_dev)) {
if (pt_prev)
ret = deliver_skb(skb?? pt_prev?? orig_dev);
pt_prev = ptype;
}
}
if (pt_prev) {
if (unlikely(skb_orphan_frags(skb?? GFP_ATOMIC)))
goto drop;
else
ret = pt_prev->func(skb?? skb->dev?? pt_prev?? orig_dev);
} else {
drop:
atomic_long_inc(&skb->dev->rx_dropped);
kfree_skb(skb);
ret = NET_RX_DROP;
}
out:
return ret;
}
??????????dev?????????bridge?????bridge????????????????????豸??rx_handler???????br_handle_frame????????????br_add_if??????????????br_add_if (net/bridge/br_if.c)???????????豸??????????????????br_handle_frame???????bridge?????????
????br_add_if
int br_add_if(struct net_bridge *br?? struct net_device *dev)
{
/*......*/
err = netdev_rx_handler_register(dev?? br_handle_frame?? p);
/*......*/
}
????br_handle_frame
rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
{
struct net_bridge_port *p;
struct sk_buff *skb = *pskb;
const unsigned char *dest = eth_hdr(skb)->h_dest;
br_should_route_hook_t *rhook;
if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
return RX_HANDLER_PASS;
if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
goto drop;
skb = skb_share_check(skb?? GFP_ATOMIC);
if (!skb)
return RX_HANDLER_CONSUMED;
/*???dev?????bridge port*/
p = br_port_get_rcu(skb->dev);
/*???????mac????????*/
if (unlikely(is_link_local_ether_addr(dest))) {
/*
* See IEEE 802.1D Table 7-10 Reserved addresses
*
* Assignment Value
* Bridge Group Address 01-80-C2-00-00-00
* (MAC Control) 802.3 01-80-C2-00-00-01
* (Link Aggregation) 802.3 01-80-C2-00-00-02
* 802.1X PAE address 01-80-C2-00-00-03
*
* 802.1AB LLDP 01-80-C2-00-00-0E
*
* Others reserved for future standardization
*/
switch (dest[5]) {
case 0x00: /* Bridge Group Address */
/* If STP is turned off??then must forward to keep loop detection */
if (p->br->stp_enabled == BR_NO_STP)
goto forward;
break;
case 0x01: /* IEEE MAC (Pause) */
goto drop;
default:
/* Allow selective forwarding for most other protocols */
if (p->br->group_fwd_mask & (1u << dest[5]))
goto forward;
}
/* LOCAL_IN hook??????????hook????????????????Э???????????????mac 01-80-C2??????????*/
if (NF_HOOK(NFPROTO_BRIDGE?? NF_BR_LOCAL_IN?? skb?? skb->dev??
NULL?? br_handle_local_finish)) {
return RX_HANDLER_CONSUMED; /* consumed by filter */
} else {
*pskb = skb;
return RX_HANDLER_PASS; /* continue processing */
}
}
/*??????*/
forward:
switch (p->state) {
case BR_STATE_FORWARDING:
rhook = rcu_dereference(br_should_route_hook);
if (rhook) {
if ((*rhook)(skb)) {
*pskb = skb;
return RX_HANDLER_PASS;
}
dest = eth_hdr(skb)->h_dest;
}
/* fall through */
case BR_STATE_LEARNING:
/*skb?????mac??bridge??mac???????skb????????Э???*/
if (ether_addr_equal(p->br->dev->dev_addr?? dest))
skb->pkt_type = PACKET_HOST;
/*NF_BR_PRE_ROUTING hook??*/
NF_HOOK(NFPROTO_BRIDGE?? NF_BR_PRE_ROUTING?? skb?? skb->dev?? NULL??br_handle_frame_finish);
break;
default:
drop:
kfree_skb(skb);
}
return RX_HANDLER_CONSUMED;
}