netif_receive_skb()

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最新推荐文章于 2022-10-06 14:37:09 发布

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本文深入探讨了Linux内核2.6.19版本中netif_receive_skb函数的实现细节，该函数负责处理接收的数据包，并通过各种过滤器进行传递。文章详细介绍了如何根据设备类型和数据包类型将数据包传递给相应的处理程序。

process_backlog() --> netif_receive_skb()

/usr/src/linux-2.6.19/net/core/dev.c

int netif_receive_skb(struct sk_buff *skb)
{
    struct packet_type *ptype, *pt_prev;
    struct net_device *orig_dev;
    int ret = NET_RX_DROP;
    unsigned short type;

    if (skb->dev->poll && netpoll_rx(skb))
        return NET_RX_DROP;
    if (!skb->tstamp.off_sec)
        net_timestamp(skb);
    if (!skb->input_dev)
        skb->input_dev = skb->dev;

    orig_dev = skb_bond(skb);
    if (!orig_dev)
        return NET_RX_DROP;

    __get_cpu_var(netdev_rx_stat).total++;
    skb->h.raw = skb->nh.raw = skb->data;
    skb->mac_len = skb->nh.raw - skb->mac.raw;
    pt_prev = NULL;
    rcu_read_lock();

#ifdef CONFIG_NET_CLS_ACT
    if (skb->tc_verd & TC_NCLS) {
        skb->tc_verd = CLR_TC_NCLS(skb->tc_verd);
        goto ncls;
    }
#endif

    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;
        }
    }

#ifdef CONFIG_NET_CLS_ACT
    if (pt_prev) {
        ret = deliver_skb(skb, pt_prev, orig_dev);
        pt_prev = NULL;
    } else {
        skb->tc_verd = SET_TC_OK2MUNGE(skb->tc_verd);
    }
    ret = ing_filter(skb);
    if (ret == TC_ACT_SHOT || (ret == TC_ACT_STOLEN)) {
        kfree_skb(skb);
        goto out;
    }
    skb->tc_verd = 0;
ncls:
#endif

    handle_diverter(skb);
    if (handle_bridge(&skb, &pt_prev, &ret, orig_dev))
        goto out;
    type = skb->protocol;

    list_for_each_entry_rcu(ptype, &ptype_base[ntohs(type)&15], list) {
        if (ptype->type == type &&
            (!ptype->dev || ptype->dev == skb->dev)) {
            if (pt_prev)
                ret = deliver_skb(skb, pt_prev, orig_dev);
            pt_prev = ptype;
        }
    }

    if (pt_prev) {
        ret = pt_prev->func (skb, skb->dev, pt_prev, orig_dev);
    } else {
        kfree_skb(skb);
        ret = NET_RX_DROP;
    }

out:
    rcu_read_unlock();
    return ret;
}