慢慢欣賞linux 網絡協定棧四 sk_buff以及資料收發

慢慢欣賞linux 網絡協定棧四 sk_buff以及資料收發

以3c359x.c的網卡為例，因為這是《深入了解Linux網絡技術内幕》裡面的例子

irqreturn_t vortex_interrupt(int irq, void *dev_id)

vortex_rx(dev);
=>int vortex_rx(struct net_device *dev)
    struct vortex_private *vp = netdev_priv(dev);
    void __iomem *ioaddr = vp->ioaddr;
    short rx_status;
    while ((rx_status = ioread16(ioaddr + RxStatus)) > 0)
        int pkt_len = rx_status & 0x1fff;
        struct sk_buff *skb = dev_alloc_skb(pkt_len + 5);
        skb_reserve(skb, 2);    /* Align IP on 16 byte boundaries */
        if (vp->bus_master && ! (ioread16(ioaddr + Wn7_MasterStatus) & 0x8000)) 
            dma_addr_t dma = pci_map_single(VORTEX_PCI(vp), skb_put(skb, pkt_len), pkt_len, PCI_DMA_FROMDEVICE);
            iowrite32(dma, ioaddr + Wn7_MasterAddr);
            iowrite16((skb->len + 3) & ~3, ioaddr + Wn7_MasterLen);
            iowrite16(StartDMAUp, ioaddr + EL3_CMD);
            while (ioread16(ioaddr + Wn7_MasterStatus) & 0x8000)
                ;
            pci_unmap_single(VORTEX_PCI(vp), dma, pkt_len, PCI_DMA_FROMDEVICE);
        else 
            ioread32_rep(ioaddr + RX_FIFO, skb_put(skb, pkt_len), (pkt_len + 3) >> 2);
            
        iowrite16(RxDiscard, ioaddr + EL3_CMD); /* Pop top Rx packet. */
        skb->protocol = eth_type_trans(skb, dev);
        netif_rx(skb)
        =>int netif_rx(struct sk_buff *skb)
            if (queue->input_pkt_queue.qlen <= netdev_max_backlog)
                if (queue->input_pkt_queue.qlen)
        enqueue:
                    __skb_queue_tail(&queue->input_pkt_queue, skb);
                    return NET_RX_SUCCESS;
                    
                napi_schedule(&queue->backlog);
                =>inline void napi_schedule(struct napi_struct *n)
                    if (napi_schedule_prep(n))
                        __napi_schedule(n);
                        =>void __napi_schedule(struct napi_struct *n)
                            list_add_tail(&n->poll_list, &__get_cpu_var(softnet_data).poll_list);
                            __raise_softirq_irqoff(NET_RX_SOFTIRQ);//喚醒軟中斷
                goto enqueue;           

收包軟中斷入口函數

void net_rx_action(struct softirq_action *h)

struct list_head *list = &__get_cpu_var(softnet_data).poll_list;
while (!list_empty(list))
    n = list_first_entry(list, struct napi_struct, poll_list);

    have = netpoll_poll_lock(n);

    weight = n->weight;
    
    n = list_first_entry(list, struct napi_struct, poll_list);

    have = netpoll_poll_lock(n);

    weight = n->weight;
    
    work = 0;
    if (test_bit(NAPI_STATE_SCHED, &n->state))
        work = n->poll(n, weight);
        =>int process_backlog(struct napi_struct *napi, int quota)
        
    budget -= work;           

Linux 網絡協定棧開發代碼分析篇之資料收發（一） —— netif_receive_skb()函數

https://blog.csdn.net/zqixiao_09/article/details/79185800

Linux核心--網絡棧實作分析（二）--資料包的傳遞過程（上）

https://blog.csdn.net/geekcome/article/details/7492423

作者：天麓

來源：CSDN

原文：

https://blog.csdn.net/shipinsky/article/details/88923786

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