【OVS2.5.0源码分析】upcall处理线程分析（1）

最新推荐文章于 2024-06-10 20:26:25 发布

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最新推荐文章于 2024-06-10 20:26:25 发布 · 2.1k 阅读

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#OVS #openvswitch #网络

本文深入探讨了OVS2.5.0中upcall处理线程的工作机制，主要关注入口函数udpif_upcall_handler。该线程通过netlink接口接收并处理由datapath上送的报文。

upcall线程处理由datapath通过netlink机制上送的报文，其入口函数为udpif_upcall_handler，这一篇我们先分析该线程是如何收取upcall报文的。

1、udpif_upcall_handler函数

/* The upcall handler thread tries to read a batch of UPCALL_MAX_BATCH
 * upcalls from dpif, processes the batch and installs corresponding flows
 * in dpif. */
static void *
udpif_upcall_handler(void *arg)
{
    struct handler *handler = arg;
    struct udpif *udpif = handler->udpif;

    while (!latch_is_set(&handler->udpif->exit_latch)) {	
        if (recv_upcalls(handler)) {
            poll_immediate_wake();     //不阻塞，说明还有upcall需要处理
        } else {
            dpif_recv_wait(udpif->dpif, handler->handler_id);     //阻塞在netlink接收上
            latch_wait(&udpif->exit_latch); 
        }
        poll_block();		//poll阻塞
    }

    return NULL;
}

2、recv_upcalls函数

static size_t
recv_upcalls(struct handler *handler)
{
    struct udpif *udpif = handler->udpif;
    uint64_t recv_stubs[UPCALL_MAX_BATCH][512 / 8];
    struct ofpbuf recv_bufs[UPCALL_MAX_BATCH];
    struct dpif_upcall dupcalls[UPCALL_MAX_BATCH];
    struct upcall upcalls[UPCALL_MAX_BATCH];
    struct flow flows[UPCALL_MAX_BATCH];
    size_t n_upcalls, i;

    n_upcalls = 0;
    while (n_upcalls < UPCALL_MAX_BATCH) {
        struct ofpbuf *recv_buf = &recv_bufs[n_upcalls];
        struct dpif_upcall *dupcall = &dupcalls[n_upcalls];
        struct upcall *upcall = &upcalls[n_upcalls];
        struct flow *flow = &flows[n_upcalls];
        unsigned int mru;
        int error;

        ofpbuf_use_stub(recv_buf, recv_stubs[n_upcalls],
                        sizeof recv_stubs[n_upcalls]);
        if (dpif_recv(udpif->dpif, handler->handler_id, dupcall, recv_buf)) {    //接收upcall报文
            ofpbuf_uninit(recv_buf);
            break;
        }

        if (odp_flow_key_to_flow(dupcall->key, dupcall->key_len, flow)
            == ODP_FIT_ERROR) {
            goto free_dupcall;
        }

        if (dupcall->mru) {
            mru = nl_attr_get_u16(dupcall->mru);
        } else {
            mru = 0;
        }

        error = upcall_receive(upcall, udpif->backer, &dupcall->packet,
                               dupcall->type, dupcall->userdata, flow, mru,
                               &dupcall->ufid, PMD_ID_NULL);
        if (error) {
            if (error == ENODEV) {
                /* Received packet on datapath port for which we couldn't
                 * associate an ofproto.  This can happen if a port is removed
                 * while traffic is being received.  Print a rate-limited
                 * message in case it happens frequently. */
                dpif_flow_put(udpif->dpif, DPIF_FP_CRE