C++ dst_hold函数代码示例

/**
 * skb_dst_set_noref - sets skb dst, without a reference
 * @skb: buffer
 * @dst: dst entry
 *
 * Sets skb dst, assuming a reference was not taken on dst
 * skb_dst_drop() should not dst_release() this dst
 */
void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
{
	WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
	/* If dst not in cache, we must take a reference, because
	 * dst_release() will destroy dst as soon as its refcount becomes zero
	 */
	if (unlikely(dst->flags & DST_NOCACHE)) {
		dst_hold(dst);
		skb_dst_set(skb, dst);
	} else {
		skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
	}
}

static inline struct dst_entry *
__ip_vs_dst_check(struct ip_vs_dest *dest, u32 rtos, u32 cookie)
{
	struct dst_entry *dst = dest->dst_cache;

	if (!dst)
		return NULL;
	if ((dst->obsolete || rtos != dest->dst_rtos) &&
	    dst->ops->check(dst, cookie) == NULL) {
		dest->dst_cache = NULL;
		return NULL;
	}
	dst_hold(dst);
	return dst;
}

static netdev_tx_t nfp_repr_xmit(struct sk_buff *skb, struct net_device *netdev)
{
	struct nfp_repr *repr = netdev_priv(netdev);
	unsigned int len = skb->len;
	int ret;

	skb_dst_drop(skb);
	dst_hold((struct dst_entry *)repr->dst);
	skb_dst_set(skb, (struct dst_entry *)repr->dst);
	skb->dev = repr->dst->u.port_info.lower_dev;

	ret = dev_queue_xmit(skb);
	nfp_repr_inc_tx_stats(netdev, len, ret);

	return NETDEV_TX_OK;
}

a_status_t
__adf_net_indicate_packet(adf_net_handle_t hdl, struct sk_buff *skb,
                          uint32_t len)
{
    struct net_device *netdev   = hdl_to_netdev(hdl);
    __adf_softc_t  *sc          = hdl_to_softc(hdl);
    /**
     * For pseudo devices IP checksum has to computed
     */
    if(adf_os_unlikely(skb->ip_summed == CHECKSUM_UNNECESSARY))
        __adf_net_ip_cksum(skb);

    /**
     * also pulls the ether header
     */
    skb->protocol           =   eth_type_trans(skb, netdev);
    skb->dev                =   netdev;
    netdev->last_rx         =   jiffies;
#ifdef LIMIT_MTU_SIZE

    if (skb->len >=  LIMITED_MTU) {
        skb->h.raw = skb->nh.raw = skb->data;

        skb->dst = (struct dst_entry *)&__fake_rtable;
        skb->pkt_type = PACKET_HOST;
        dst_hold(skb->dst);

#if 0
        printk("addrs : sa : %x : da:%x\n", skb->nh.iph->saddr, skb->nh.iph->daddr);
        printk("head : %p tail : %p iph %p %p\n", skb->head, skb->tail,
                skb->nh.iph, skb->mac.raw);
#endif 

        icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(LIMITED_MTU - 4 ));
        dev_kfree_skb_any(skb);
        return A_STATUS_OK;
    }
#endif


    
    if(sc->vlgrp)       __vlan_hwaccel_put_tag(skb, sc->vid);
    if (in_irq())  	netif_rx(skb);
    else                netif_receive_skb(skb);

    return A_STATUS_OK;
}

static struct rtable *vrf_get_rtable(const struct net_device *dev,
				     const struct flowi4 *fl4)
{
	struct rtable *rth = NULL;

	if (!(fl4->flowi4_flags & FLOWI_FLAG_L3MDEV_SRC)) {
		struct net_vrf *vrf = netdev_priv(dev);

		rcu_read_lock();

		rth = rcu_dereference(vrf->rth);
		if (likely(rth))
			dst_hold(&rth->dst);

		rcu_read_unlock();
	}

	return rth;
}

/* Undo the changes made for ip6tables PREROUTING and continue the
 * bridge PRE_ROUTING hook. */
static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
{
	struct nf_bridge_info *nf_bridge = skb->nf_bridge;

	if (nf_bridge->mask & BRNF_PKT_TYPE) {
		skb->pkt_type = PACKET_OTHERHOST;
		nf_bridge->mask ^= BRNF_PKT_TYPE;
	}
	nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;

	skb->dst = (struct dst_entry *)&__fake_rtable;
	dst_hold(skb->dst);

	skb->dev = nf_bridge->physindev;
	nf_bridge_push_encap_header(skb);
	NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
		       br_handle_frame_finish, 1);

	return 0;
}

struct rt6_info *rt6_lookup(struct in6_addr *daddr, struct in6_addr *saddr,
			    int oif, int flags)
{
	struct fib6_node *fn;
	struct rt6_info *rt;

	read_lock_bh(&rt6_lock);
	fn = fib6_lookup(&ip6_routing_table, daddr, saddr);
	rt = rt6_device_match(fn->leaf, oif, !!(flags & RT6_LOOKUP_FLAG_STRICT));
	dst_hold(&rt->u.dst);
	rt->u.dst.__use++;
	read_unlock_bh(&rt6_lock);

	if (!(flags & RT6_LOOKUP_FLAG_NOUSE))
		rt->u.dst.lastuse = jiffies;
	if (rt->u.dst.error == 0)
		return rt;
	dst_release(&rt->u.dst);
	return NULL;
}

void ipv6_ac_destroy_dev(struct inet6_dev *idev)
{
	struct ifacaddr6 *aca;

	write_lock_bh(&idev->lock);
	while ((aca = idev->ac_list) != NULL) {
		idev->ac_list = aca->aca_next;
		write_unlock_bh(&idev->lock);

		addrconf_leave_solict(idev, &aca->aca_addr);

		dst_hold(&aca->aca_rt->dst);
		ip6_del_rt(aca->aca_rt);

		aca_put(aca);

		write_lock_bh(&idev->lock);
	}
	write_unlock_bh(&idev->lock);
}

static struct dst_entry *rxe_find_route(struct net_device *ndev,
					struct rxe_qp *qp,
					struct rxe_av *av)
{
	struct dst_entry *dst = NULL;

	if (qp_type(qp) == IB_QPT_RC)
		dst = sk_dst_get(qp->sk->sk);

	if (!dst || !dst_check(dst, qp->dst_cookie)) {
		if (dst)
			dst_release(dst);

		if (av->network_type == RDMA_NETWORK_IPV4) {
			struct in_addr *saddr;
			struct in_addr *daddr;

			saddr = &av->sgid_addr._sockaddr_in.sin_addr;
			daddr = &av->dgid_addr._sockaddr_in.sin_addr;
			dst = rxe_find_route4(ndev, saddr, daddr);
		} else if (av->network_type == RDMA_NETWORK_IPV6) {
			struct in6_addr *saddr6;
			struct in6_addr *daddr6;

			saddr6 = &av->sgid_addr._sockaddr_in6.sin6_addr;
			daddr6 = &av->dgid_addr._sockaddr_in6.sin6_addr;
			dst = rxe_find_route6(ndev, saddr6, daddr6);
#if IS_ENABLED(CONFIG_IPV6)
			if (dst)
				qp->dst_cookie =
					rt6_get_cookie((struct rt6_info *)dst);
#endif
		}

		if (dst && (qp_type(qp) == IB_QPT_RC)) {
			dst_hold(dst);
			sk_dst_set(qp->sk->sk, dst);
		}
	}
	return dst;
}

/* Undo the changes made for ip6tables PREROUTING and continue the
 * bridge PRE_ROUTING hook. */
static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
{
	struct nf_bridge_info *nf_bridge = skb->nf_bridge;

	if (nf_bridge->mask & BRNF_PKT_TYPE) {
		skb->pkt_type = PACKET_OTHERHOST;
		nf_bridge->mask ^= BRNF_PKT_TYPE;
	}
	nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;

	skb->dst = (struct dst_entry *)&__fake_rtable;
	dst_hold(skb->dst);

	skb->dev = nf_bridge->physindev;
	if (skb->protocol == htons(ETH_P_8021Q)) {
		skb_push(skb, VLAN_HLEN);
		skb->nh.raw -= VLAN_HLEN;
	}
	NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
		       br_handle_frame_finish, 1);

	return 0;
}

int ip_xfrm_me_harder(struct sk_buff **pskb)
{
	struct flowi fl;
	unsigned int hh_len;
	struct dst_entry *dst;

	if (IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED)
		return 0;
	if (xfrm_decode_session(*pskb, &fl, AF_INET) < 0)
		return -1;

	dst = (*pskb)->dst;
	if (dst->xfrm)
		dst = ((struct xfrm_dst *)dst)->route;
	dst_hold(dst);

	if (xfrm_lookup(&dst, &fl, (*pskb)->sk, 0) < 0)
		return -1;

	dst_release((*pskb)->dst);
	(*pskb)->dst = dst;

	/* Change in oif may mean change in hh_len. */
	hh_len = (*pskb)->dst->dev->hard_header_len;
	if (skb_headroom(*pskb) < hh_len) {
		struct sk_buff *nskb;

		nskb = skb_realloc_headroom(*pskb, hh_len);
		if (!nskb)
			return -1;
		if ((*pskb)->sk)
			skb_set_owner_w(nskb, (*pskb)->sk);
		kfree_skb(*pskb);
		*pskb = nskb;
	}
	return 0;
}

static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
		u8 type, u8 code, int offset, __be32 info)
{
	const struct ipv6hdr *hdr = (const struct ipv6hdr*)skb->data;
	const struct tcphdr *th = (struct tcphdr *)(skb->data+offset);
	struct ipv6_pinfo *np;
	struct sock *sk;
	int err;
	struct tcp_sock *tp;
	__u32 seq;
	struct net *net = dev_net(skb->dev);

	sk = inet6_lookup(net, &tcp_hashinfo, &hdr->daddr,
			th->dest, &hdr->saddr, th->source, skb->dev->ifindex);

	if (sk == NULL) {
		ICMP6_INC_STATS_BH(net, __in6_dev_get(skb->dev),
				   ICMP6_MIB_INERRORS);
		return;
	}

	if (sk->sk_state == TCP_TIME_WAIT) {
		inet_twsk_put(inet_twsk(sk));
		return;
	}

	bh_lock_sock(sk);
	if (sock_owned_by_user(sk))
		NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);

	if (sk->sk_state == TCP_CLOSE)
		goto out;

	if (ipv6_hdr(skb)->hop_limit < inet6_sk(sk)->min_hopcount) {
		NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
		goto out;
	}

	tp = tcp_sk(sk);
	seq = ntohl(th->seq);
	if (sk->sk_state != TCP_LISTEN &&
	    !between(seq, tp->snd_una, tp->snd_nxt)) {
		NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
		goto out;
	}

	np = inet6_sk(sk);

	if (type == ICMPV6_PKT_TOOBIG) {
		struct dst_entry *dst;

		if (sock_owned_by_user(sk))
			goto out;
		if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))
			goto out;

		
		dst = __sk_dst_check(sk, np->dst_cookie);

		if (dst == NULL) {
			struct inet_sock *inet = inet_sk(sk);
			struct flowi6 fl6;

			memset(&fl6, 0, sizeof(fl6));
			fl6.flowi6_proto = IPPROTO_TCP;
			fl6.daddr = np->daddr;
			fl6.saddr = np->saddr;
			fl6.flowi6_oif = sk->sk_bound_dev_if;
			fl6.flowi6_mark = sk->sk_mark;
			fl6.fl6_dport = inet->inet_dport;
			fl6.fl6_sport = inet->inet_sport;
			fl6.flowi6_uid = sock_i_uid(sk);
			security_skb_classify_flow(skb, flowi6_to_flowi(&fl6));

			dst = ip6_dst_lookup_flow(sk, &fl6, NULL, false);
			if (IS_ERR(dst)) {
				sk->sk_err_soft = -PTR_ERR(dst);
				goto out;
			}

		} else
			dst_hold(dst);

		if (inet_csk(sk)->icsk_pmtu_cookie > dst_mtu(dst)) {
			tcp_sync_mss(sk, dst_mtu(dst));
			tcp_simple_retransmit(sk);
		} 
		dst_release(dst);
		goto out;
	}

	icmpv6_err_convert(type, code, &err);

	
	switch (sk->sk_state) {
		struct request_sock *req, **prev;
	case TCP_LISTEN:
		if (sock_owned_by_user(sk))
			goto out;

//.........这里部分代码省略.........

static int
__xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
		      struct flowi *fl, struct dst_entry **dst_p)
{
	struct dst_entry *dst, *dst_prev;
	struct rtable *rt0 = (struct rtable*)(*dst_p);
	struct rtable *rt = rt0;
	struct flowi fl_tunnel = {
		.nl_u = {
			.ip4_u = {
				.saddr = fl->fl4_src,
				.daddr = fl->fl4_dst,
				.tos = fl->fl4_tos
			}
		}
	};
	int i;
	int err;
	int header_len = 0;
	int trailer_len = 0;

	dst = dst_prev = NULL;
	dst_hold(&rt->u.dst);

	for (i = 0; i < nx; i++) {
		struct dst_entry *dst1 = dst_alloc(&xfrm4_dst_ops);
		struct xfrm_dst *xdst;

		if (unlikely(dst1 == NULL)) {
			err = -ENOBUFS;
			dst_release(&rt->u.dst);
			goto error;
		}

		if (!dst)
			dst = dst1;
		else {
			dst_prev->child = dst1;
			dst1->flags |= DST_NOHASH;
			dst_clone(dst1);
		}

		xdst = (struct xfrm_dst *)dst1;
		xdst->route = &rt->u.dst;
		xdst->genid = xfrm[i]->genid;

		dst1->next = dst_prev;
		dst_prev = dst1;

		header_len += xfrm[i]->props.header_len;
		trailer_len += xfrm[i]->props.trailer_len;

		if (xfrm[i]->props.mode == XFRM_MODE_TUNNEL) {
			unsigned short encap_family = xfrm[i]->props.family;
			switch(encap_family) {
			case AF_INET:
				fl_tunnel.fl4_dst = xfrm[i]->id.daddr.a4;
				fl_tunnel.fl4_src = xfrm[i]->props.saddr.a4;
				break;
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
			case AF_INET6:
				ipv6_addr_copy(&fl_tunnel.fl6_dst, (struct in6_addr*)&xfrm[i]->id.daddr.a6);
				ipv6_addr_copy(&fl_tunnel.fl6_src, (struct in6_addr*)&xfrm[i]->props.saddr.a6);
				break;
#endif
			default:
				BUG_ON(1);
			}
			err = xfrm_dst_lookup((struct xfrm_dst **)&rt,
					      &fl_tunnel, encap_family);
			if (err)
				goto error;
		} else
			dst_hold(&rt->u.dst);
	}

	dst_prev->child = &rt->u.dst;
	dst->path = &rt->u.dst;

	*dst_p = dst;
	dst = dst_prev;

	dst_prev = *dst_p;
	i = 0;
	for (; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
		struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
		struct xfrm_state_afinfo *afinfo;
		x->u.rt.fl = *fl;

		dst_prev->xfrm = xfrm[i++];
		dst_prev->dev = rt->u.dst.dev;
		if (rt->u.dst.dev)
			dev_hold(rt->u.dst.dev);
		dst_prev->obsolete	= -1;
		dst_prev->flags	       |= DST_HOST;
		dst_prev->lastuse	= jiffies;
		dst_prev->header_len	= header_len;
		dst_prev->nfheader_len	= 0;
		dst_prev->trailer_len	= trailer_len;
		memcpy(&dst_prev->metrics, &x->route->metrics, sizeof(dst_prev->metrics));
//.........这里部分代码省略.........

int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
	int offset, int len, int odd, struct sk_buff *skb),
	void *from, int length, int transhdrlen,
	int hlimit, int tclass, struct ipv6_txoptions *opt, struct flowi6 *fl6,
	struct rt6_info *rt, unsigned int flags, int dontfrag)
{
	struct inet_sock *inet = inet_sk(sk);
	struct ipv6_pinfo *np = inet6_sk(sk);
	struct inet_cork *cork;
	struct sk_buff *skb, *skb_prev = NULL;
	unsigned int maxfraglen, fragheaderlen;
	int exthdrlen;
	int hh_len;
	int mtu;
	int copy;
	int err;
	int offset = 0;
	int csummode = CHECKSUM_NONE;
	__u8 tx_flags = 0;

	if (flags&MSG_PROBE)
		return 0;
	cork = &inet->cork.base;
	if (skb_queue_empty(&sk->sk_write_queue)) {
		/*
		 * setup for corking
		 */
		if (opt) {
			if (WARN_ON(np->cork.opt))
				return -EINVAL;

			np->cork.opt = kzalloc(opt->tot_len, sk->sk_allocation);
			if (unlikely(np->cork.opt == NULL))
				return -ENOBUFS;

			np->cork.opt->tot_len = opt->tot_len;
			np->cork.opt->opt_flen = opt->opt_flen;
			np->cork.opt->opt_nflen = opt->opt_nflen;

			np->cork.opt->dst0opt = ip6_opt_dup(opt->dst0opt,
							    sk->sk_allocation);
			if (opt->dst0opt && !np->cork.opt->dst0opt)
				return -ENOBUFS;

			np->cork.opt->dst1opt = ip6_opt_dup(opt->dst1opt,
							    sk->sk_allocation);
			if (opt->dst1opt && !np->cork.opt->dst1opt)
				return -ENOBUFS;

			np->cork.opt->hopopt = ip6_opt_dup(opt->hopopt,
							   sk->sk_allocation);
			if (opt->hopopt && !np->cork.opt->hopopt)
				return -ENOBUFS;

			np->cork.opt->srcrt = ip6_rthdr_dup(opt->srcrt,
							    sk->sk_allocation);
			if (opt->srcrt && !np->cork.opt->srcrt)
				return -ENOBUFS;

			/* need source address above miyazawa*/
		}
		dst_hold(&rt->dst);
		cork->dst = &rt->dst;
		inet->cork.fl.u.ip6 = *fl6;
		np->cork.hop_limit = hlimit;
		np->cork.tclass = tclass;
		if (rt->dst.flags & DST_XFRM_TUNNEL)
			mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ?
			      rt->dst.dev->mtu : dst_mtu(&rt->dst);
		else
			mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ?
			      rt->dst.dev->mtu : dst_mtu(rt->dst.path);
		if (np->frag_size < mtu) {
			if (np->frag_size)
				mtu = np->frag_size;
		}
		cork->fragsize = mtu;
		if (dst_allfrag(rt->dst.path))
			cork->flags |= IPCORK_ALLFRAG;
		cork->length = 0;
		sk->sk_sndmsg_page = NULL;
		sk->sk_sndmsg_off = 0;
		exthdrlen = rt->dst.header_len + (opt ? opt->opt_flen : 0) -
			    rt->rt6i_nfheader_len;
		length += exthdrlen;
		transhdrlen += exthdrlen;
	} else {
		rt = (struct rt6_info *)cork->dst;
		fl6 = &inet->cork.fl.u.ip6;
		opt = np->cork.opt;
		transhdrlen = 0;
		exthdrlen = 0;
		mtu = cork->fragsize;
	}

	hh_len = LL_RESERVED_SPACE(rt->dst.dev);

	fragheaderlen = sizeof(struct ipv6hdr) + rt->rt6i_nfheader_len +
			(opt ? opt->opt_nflen : 0);
	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen - sizeof(struct frag_hdr);
//.........这里部分代码省略.........

static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
			  struct inet6_cork *v6_cork,
			  int hlimit, int tclass, struct ipv6_txoptions *opt,
			  struct rt6_info *rt, struct flowi6 *fl6)
{
	struct ipv6_pinfo *np = inet6_sk(sk);
	unsigned int mtu;

	/*
	 * setup for corking
	 */
	if (opt) {
		if (WARN_ON(v6_cork->opt))
			return -EINVAL;

		v6_cork->opt = kzalloc(opt->tot_len, sk->sk_allocation);
		if (unlikely(!v6_cork->opt))
			return -ENOBUFS;

		v6_cork->opt->tot_len = opt->tot_len;
		v6_cork->opt->opt_flen = opt->opt_flen;
		v6_cork->opt->opt_nflen = opt->opt_nflen;

		v6_cork->opt->dst0opt = ip6_opt_dup(opt->dst0opt,
						    sk->sk_allocation);
		if (opt->dst0opt && !v6_cork->opt->dst0opt)
			return -ENOBUFS;

		v6_cork->opt->dst1opt = ip6_opt_dup(opt->dst1opt,
						    sk->sk_allocation);
		if (opt->dst1opt && !v6_cork->opt->dst1opt)
			return -ENOBUFS;

		v6_cork->opt->hopopt = ip6_opt_dup(opt->hopopt,
						   sk->sk_allocation);
		if (opt->hopopt && !v6_cork->opt->hopopt)
			return -ENOBUFS;

		v6_cork->opt->srcrt = ip6_rthdr_dup(opt->srcrt,
						    sk->sk_allocation);
		if (opt->srcrt && !v6_cork->opt->srcrt)
			return -ENOBUFS;

		/* need source address above miyazawa*/
	}
	dst_hold(&rt->dst);
	cork->base.dst = &rt->dst;
	cork->fl.u.ip6 = *fl6;
	v6_cork->hop_limit = hlimit;
	v6_cork->tclass = tclass;
	if (rt->dst.flags & DST_XFRM_TUNNEL)
		mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
		      rt->dst.dev->mtu : dst_mtu(&rt->dst);
	else
		mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
		      rt->dst.dev->mtu : dst_mtu(rt->dst.path);
	if (np->frag_size < mtu) {
		if (np->frag_size)
			mtu = np->frag_size;
	}
	cork->base.fragsize = mtu;
	if (dst_allfrag(rt->dst.path))
		cork->base.flags |= IPCORK_ALLFRAG;
	cork->base.length = 0;

	return 0;
}