/* * Common framework for low-level network console, dump, and debugger code * * Sep 8 2003 Matt Mackall <mpm@selenic.com> * * based on the netconsole code from: * * Copyright (C) 2001 Ingo Molnar <mingo@redhat.com> * Copyright (C) 2002 Red Hat, Inc. */ #include <linux/moduleparam.h> #include <linux/netdevice.h> #include <linux/etherdevice.h> #include <linux/string.h> #include <linux/if_arp.h> #include <linux/inetdevice.h> #include <linux/inet.h> #include <linux/interrupt.h> #include <linux/netpoll.h> #include <linux/sched.h> #include <linux/delay.h> #include <linux/rcupdate.h> #include <linux/workqueue.h> #include <linux/slab.h> #include <linux/export.h> #include <net/tcp.h> #include <net/udp.h> #include <asm/unaligned.h> #include <trace/events/napi.h> /* * We maintain a small pool of fully-sized skbs, to make sure the * message gets out even in extreme OOM situations. */ #define MAX_UDP_CHUNK 1460 #define MAX_SKBS 32 static struct sk_buff_head skb_pool; static atomic_t trapped; #define USEC_PER_POLL 50 #define NETPOLL_RX_ENABLED 1 #define NETPOLL_RX_DROP 2 #define MAX_SKB_SIZE \ (MAX_UDP_CHUNK + sizeof(struct udphdr) + \ sizeof(struct iphdr) + sizeof(struct ethhdr)) static void zap_completion_queue(void); static void arp_reply(struct sk_buff *skb); static unsigned int carrier_timeout = 4; module_param(carrier_timeout, uint, 0644); static void queue_process(struct work_struct *work) { struct netpoll_info *npinfo = container_of(work, struct netpoll_info, tx_work.work); struct sk_buff *skb; unsigned long flags; while ((skb = skb_dequeue(&npinfo->txq))) { struct net_device *dev = skb->dev; const struct net_device_ops *ops = dev->netdev_ops; struct netdev_queue *txq; if (!netif_device_present(dev) || !netif_running(dev)) { __kfree_skb(skb); continue; } txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb)); local_irq_save(flags); __netif_tx_lock(txq, smp_processor_id()); if (netif_xmit_frozen_or_stopped(txq) || ops->ndo_start_xmit(skb, dev) != NETDEV_TX_OK) { skb_queue_head(&npinfo->txq, skb); __netif_tx_unlock(txq); local_irq_restore(flags); schedule_delayed_work(&npinfo->tx_work, HZ/10); return; } __netif_tx_unlock(txq); local_irq_restore(flags); } } static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh, unsigned short ulen, __be32 saddr, __be32 daddr) { __wsum psum; if (uh->check == 0 || skb_csum_unnecessary(skb)) return 0; psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0); if (skb->ip_summed == CHECKSUM_COMPLETE && !csum_fold(csum_add(psum, skb->csum))) return 0; skb->csum = psum; return __skb_checksum_complete(skb); } /* * Check whether delayed processing was scheduled for our NIC. If so, * we attempt to grab the poll lock and use ->poll() to pump the card. * If this fails, either we've recursed in ->poll() or it's already * running on another CPU. * * Note: we don't mask interrupts with this lock because we're using * trylock here and interrupts are already disabled in the softirq * case. Further, we test the poll_owner to avoid recursion on UP * systems where the lock doesn't exist. * * In cases where there is bi-directional communications, reading only * one message at a time can lead to packets being dropped by the * network adapter, forcing superfluous retries and possibly timeouts. * Thus, we set our budget to greater than 1. */ static int poll_one_napi(struct netpoll_info *npinfo, struct napi_struct *napi, int budget) { int work; /* net_rx_action's ->poll() invocations and our's are * synchronized by this test which is only made while * holding the napi->poll_lock. */ if (!test_bit(NAPI_STATE_SCHED, &napi->state)) return budget; npinfo->rx_flags |= NETPOLL_RX_DROP; atomic_inc(&trapped); set_bit(NAPI_STATE_NPSVC, &napi->state); work = napi->poll(napi, budget); trace_napi_poll(napi); clear_bit(NAPI_STATE_NPSVC, &napi->state); atomic_dec(&trapped); npinfo->rx_flags &= ~NETPOLL_RX_DROP; return budget - work; } static void poll_napi(struct net_device *dev) { struct napi_struct *napi; int budget = 16; list_for_each_entry(napi, &dev->napi_list, dev_list) { if (napi->poll_owner != smp_processor_id() && spin_trylock(&napi->poll_lock)) { budget = poll_one_napi(dev->npinfo, napi, budget); spin_unlock(&napi->poll_lock); if (!budget) break; } } } static void service_arp_queue(struct netpoll_info *npi) { if (npi) { struct sk_buff *skb; while ((skb = skb_dequeue(&npi->arp_tx))) arp_reply(skb); } } static void netpoll_poll_dev(struct net_device *dev) { const struct net_device_ops *ops; if (!dev || !netif_running(dev)) return; ops = dev->netdev_ops; if (!ops->ndo_poll_controller) return; /* Process pending work on NIC */ ops->ndo_poll_controller(dev); poll_napi(dev); if (dev->priv_flags & IFF_SLAVE) { if (dev->npinfo) { struct net_device *bond_dev = dev->master; struct sk_buff *skb; while ((skb = skb_dequeue(&dev->npinfo->arp_tx))) { skb->dev = bond_dev; skb_queue_tail(&bond_dev->npinfo->arp_tx, skb); } } } service_arp_queue(dev->npinfo); zap_completion_queue(); } static void refill_skbs(void) { struct sk_buff *skb; unsigned long flags; spin_lock_irqsave(&skb_pool.lock, flags); while (skb_pool.qlen < MAX_SKBS) { skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC); if (!skb) break; __skb_queue_tail(&skb_pool, skb); } spin_unlock_irqrestore(&skb_pool.lock, flags); } static void zap_completion_queue(void) { unsigned long flags; struct softnet_data *sd = &get_cpu_var(softnet_data); if (sd->completion_queue) { struct sk_buff *clist; local_irq_save(flags); clist = sd->completion_queue; sd->completion_queue = NULL; local_irq_restore(flags); while (clist != NULL) { struct sk_buff *skb = clist; clist = clist->next; if (skb->destructor) { atomic_inc(&skb->users); dev_kfree_skb_any(skb); /* put this one back */ } else { __kfree_skb(skb); } } } put_cpu_var(softnet_data); } static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve) { int count = 0; struct sk_buff *skb; zap_completion_queue(); refill_skbs(); repeat: skb = alloc_skb(len, GFP_ATOMIC); if (!skb) skb = skb_dequeue(&skb_pool); if (!skb) { if (++count < 10) { netpoll_poll_dev(np->dev); goto repeat; } return NULL; } atomic_set(&skb->users, 1); skb_reserve(skb, reserve); return skb; } static int netpoll_owner_active(struct net_device *dev) { struct napi_struct *napi; list_for_each_entry(napi, &dev->napi_list, dev_list) { if (napi->poll_owner == smp_processor_id()) return 1; } return 0; } void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb, struct net_device *dev) { int status = NETDEV_TX_BUSY; unsigned long tries; const struct net_device_ops *ops = dev->netdev_ops; /* It is up to the caller to keep npinfo alive. */ struct netpoll_info *npinfo = np->dev->npinfo; if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) { __kfree_skb(skb); return; } /* don't get messages out of order, and no recursion */ if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) { struct netdev_queue *txq; unsigned long flags; txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb)); local_irq_save(flags); /* try until next clock tick */ for (tries = jiffies_to_usecs(1)/USEC_PER_POLL; tries > 0; --tries) { if (__netif_tx_trylock(txq)) { if (!netif_xmit_stopped(txq)) { status = ops->ndo_start_xmit(skb, dev); if (status == NETDEV_TX_OK) txq_trans_update(txq); } __netif_tx_unlock(txq); if (status == NETDEV_TX_OK) break; } /* tickle device maybe there is some cleanup */ netpoll_poll_dev(np->dev); udelay(USEC_PER_POLL); } WARN_ONCE(!irqs_disabled(), "netpoll_send_skb(): %s enabled interrupts in poll (%pF)\n", dev->name, ops->ndo_start_xmit); local_irq_restore(flags); } if (status != NETDEV_TX_OK) { skb_queue_tail(&npinfo->txq, skb); schedule_delayed_work(&npinfo->tx_work,0); } } EXPORT_SYMBOL(netpoll_send_skb_on_dev); void netpoll_send_udp(struct netpoll *np, const char *msg, int len) { int total_len, eth_len, ip_len, udp_len; struct sk_buff *skb; struct udphdr *udph; struct iphdr *iph; struct ethhdr *eth; udp_len = len + sizeof(*udph); ip_len = eth_len = udp_len + sizeof(*iph); total_len = eth_len + ETH_HLEN + NET_IP_ALIGN; skb = find_skb(np, total_len, total_len - len); if (!skb) return; skb_copy_to_linear_data(skb, msg, len); skb->len += len; skb_push(skb, sizeof(*udph)); skb_reset_transport_header(skb); udph = udp_hdr(skb); udph->source = htons(np->local_port); udph->dest = htons(np->remote_port); udph->len = htons(udp_len); udph->check = 0; udph->check = csum_tcpudp_magic(np->local_ip, np->remote_ip, udp_len, IPPROTO_UDP, csum_partial(udph, udp_len, 0)); if (udph->check == 0) udph->check = CSUM_MANGLED_0; skb_push(skb, sizeof(*iph)); skb_reset_network_header(skb); iph = ip_hdr(skb); /* iph->version = 4; iph->ihl = 5; */ put_unaligned(0x45, (unsigned char *)iph); iph->tos = 0; put_unaligned(htons(ip_len), &(iph->tot_len)); iph->id = 0; iph->frag_off = 0; iph->ttl = 64; iph->protocol = IPPROTO_UDP; iph->check = 0; put_unaligned(np->local_ip, &(iph->saddr)); put_unaligned(np->remote_ip, &(iph->daddr)); iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); eth = (struct ethhdr *) skb_push(skb, ETH_HLEN); skb_reset_mac_header(skb); skb->protocol = eth->h_proto = htons(ETH_P_IP); memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN); memcpy(eth->h_dest, np->remote_mac, ETH_ALEN); skb->dev = np->dev; netpoll_send_skb(np, skb); } EXPORT_SYMBOL(netpoll_send_udp); static void arp_reply(struct sk_buff *skb) { struct netpoll_info *npinfo = skb->dev->npinfo; struct arphdr *arp; unsigned char *arp_ptr; int size, type = ARPOP_REPLY, ptype = ETH_P_ARP; __be32 sip, tip; unsigned char *sha; struct sk_buff *send_skb; struct netpoll *np, *tmp; unsigned long flags; int hlen, tlen; int hits = 0; if (list_empty(&npinfo->rx_np)) return; /* Before checking the packet, we do some early inspection whether this is interesting at all */ spin_lock_irqsave(&npinfo->rx_lock, flags); list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) { if (np->dev == skb->dev) hits++; } spin_unlock_irqrestore(&npinfo->rx_lock, flags); /* No netpoll struct is using this dev */ if (!hits) return; /* No arp on this interface */ if (skb->dev->flags & IFF_NOARP) return; if (!pskb_may_pull(skb, arp_hdr_len(skb->dev))) return; skb_reset_network_header(skb); skb_reset_transport_header(skb); arp = arp_hdr(skb); if ((arp->ar_hrd != htons(ARPHRD_ETHER) && arp->ar_hrd != htons(ARPHRD_IEEE802)) || arp->ar_pro != htons(ETH_P_IP) || arp->ar_op != htons(ARPOP_REQUEST)) return; arp_ptr = (unsigned char *)(arp+1); /* save the location of the src hw addr */ sha = arp_ptr; arp_ptr += skb->dev->addr_len; memcpy(&sip, arp_ptr, 4); arp_ptr += 4; /* If we actually cared about dst hw addr, it would get copied here */ arp_ptr += skb->dev->addr_len; memcpy(&tip, arp_ptr, 4); /* Should we ignore arp? */ if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip)) return; size = arp_hdr_len(skb->dev); spin_lock_irqsave(&npinfo->rx_lock, flags); list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) { if (tip != np->local_ip) continue; hlen = LL_RESERVED_SPACE(np->dev); tlen = np->dev->needed_tailroom; send_skb = find_skb(np, size + hlen + tlen, hlen); if (!send_skb) continue; skb_reset_network_header(send_skb); arp = (struct arphdr *) skb_put(send_skb, size); send_skb->dev = skb->dev; send_skb->protocol = htons(ETH_P_ARP); /* Fill the device header for the ARP frame */ if (dev_hard_header(send_skb, skb->dev, ptype, sha, np->dev->dev_addr, send_skb->len) < 0) { kfree_skb(send_skb); continue; } /* * Fill out the arp protocol part. * * we only support ethernet device type, * which (according to RFC 1390) should * always equal 1 (Ethernet). */ arp->ar_hrd = htons(np->dev->type); arp->ar_pro = htons(ETH_P_IP); arp->ar_hln = np->dev->addr_len; arp->ar_pln = 4; arp->ar_op = htons(type); arp_ptr = (unsigned char *)(arp + 1); memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len); arp_ptr += np->dev->addr_len; memcpy(arp_ptr, &tip, 4); arp_ptr += 4; memcpy(arp_ptr, sha, np->dev->addr_len); arp_ptr += np->dev->addr_len; memcpy(arp_ptr, &sip, 4); netpoll_send_skb(np, send_skb); /* If there are several rx_hooks for the same address, we're fine by sending a single reply */ break; } spin_unlock_irqrestore(&npinfo->rx_lock, flags); } int __netpoll_rx(struct sk_buff *skb) { int proto, len, ulen; int hits = 0; const struct iphdr *iph; struct udphdr *uh; struct netpoll_info *npinfo = skb->dev->npinfo; struct netpoll *np, *tmp; if (list_empty(&npinfo->rx_np)) goto out; if (skb->dev->type != ARPHRD_ETHER) goto out; /* check if netpoll clients need ARP */ if (skb->protocol == htons(ETH_P_ARP) && atomic_read(&trapped)) { skb_queue_tail(&npinfo->arp_tx, skb); return 1; } proto = ntohs(eth_hdr(skb)->h_proto); if (proto != ETH_P_IP) goto out; if (skb->pkt_type == PACKET_OTHERHOST) goto out; if (skb_shared(skb)) goto out; if (!pskb_may_pull(skb, sizeof(struct iphdr))) goto out; iph = (struct iphdr *)skb->data; if (iph->ihl < 5 || iph->version != 4) goto out; if (!pskb_may_pull(skb, iph->ihl*4)) goto out; iph = (struct iphdr *)skb->data; if (ip_fast_csum((u8 *)iph, iph->ihl) != 0) goto out; len = ntohs(iph->tot_len); if (skb->len < len || len < iph->ihl*4) goto out; /* * Our transport medium may have padded the buffer out. * Now We trim to the true length of the frame. */ if (pskb_trim_rcsum(skb, len)) goto out; iph = (struct iphdr *)skb->data; if (iph->protocol != IPPROTO_UDP) goto out; len -= iph->ihl*4; uh = (struct udphdr *)(((char *)iph) + iph->ihl*4); ulen = ntohs(uh->len); if (ulen != len) goto out; if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr)) goto out; list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) { if (np->local_ip && np->local_ip != iph->daddr) continue; if (np->remote_ip && np->remote_ip != iph->saddr) continue; if (np->local_port && np->local_port != ntohs(uh->dest)) continue; np->rx_hook(np, ntohs(uh->source), (char *)(uh+1), ulen - sizeof(struct udphdr)); hits++; } if (!hits) goto out; kfree_skb(skb); return 1; out: if (atomic_read(&trapped)) { kfree_skb(skb); return 1; } return 0; } void netpoll_print_options(struct netpoll *np) { printk(KERN_INFO "%s: local port %d\n", np->name, np->local_port); printk(KERN_INFO "%s: local IP %pI4\n", np->name, &np->local_ip); printk(KERN_INFO "%s: interface '%s'\n", np->name, np->dev_name); printk(KERN_INFO "%s: remote port %d\n", np->name, np->remote_port); printk(KERN_INFO "%s: remote IP %pI4\n", np->name, &np->remote_ip); printk(KERN_INFO "%s: remote ethernet address %pM\n", np->name, np->remote_mac); } EXPORT_SYMBOL(netpoll_print_options); int netpoll_parse_options(struct netpoll *np, char *opt) { char *cur=opt, *delim; if (*cur != '@') { if ((delim = strchr(cur, '@')) == NULL) goto parse_failed; *delim = 0; np->local_port = simple_strtol(cur, NULL, 10); cur = delim; } cur++; if (*cur != '/') { if ((delim = strchr(cur, '/')) == NULL) goto parse_failed; *delim = 0; np->local_ip = in_aton(cur); cur = delim; } cur++; if (*cur != ',') { /* parse out dev name */ if ((delim = strchr(cur, ',')) == NULL) goto parse_failed; *delim = 0; strlcpy(np->dev_name, cur, sizeof(np->dev_name)); cur = delim; } cur++; if (*cur != '@') { /* dst port */ if ((delim = strchr(cur, '@')) == NULL) goto parse_failed; *delim = 0; if (*cur == ' ' || *cur == '\t') printk(KERN_INFO "%s: warning: whitespace" "is not allowed\n", np->name); np->remote_port = simple_strtol(cur, NULL, 10); cur = delim; } cur++; /* dst ip */ if ((delim = strchr(cur, '/')) == NULL) goto parse_failed; *delim = 0; np->remote_ip = in_aton(cur); cur = delim + 1; if (*cur != 0) { /* MAC address */ if (!mac_pton(cur, np->remote_mac)) goto parse_failed; } netpoll_print_options(np); return 0; parse_failed: printk(KERN_INFO "%s: couldn't parse config at '%s'!\n", np->name, cur); return -1; } EXPORT_SYMBOL(netpoll_parse_options); int __netpoll_setup(struct netpoll *np) { struct net_device *ndev = np->dev; struct netpoll_info *npinfo; const struct net_device_ops *ops; unsigned long flags; int err; if ((ndev->priv_flags & IFF_DISABLE_NETPOLL) || !ndev->netdev_ops->ndo_poll_controller) { printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n", np->name, np->dev_name); err = -ENOTSUPP; goto out; } if (!ndev->npinfo) { npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL); if (!npinfo) { err = -ENOMEM; goto out; } npinfo->rx_flags = 0; INIT_LIST_HEAD(&npinfo->rx_np); spin_lock_init(&npinfo->rx_lock); skb_queue_head_init(&npinfo->arp_tx); skb_queue_head_init(&npinfo->txq); INIT_DELAYED_WORK(&npinfo->tx_work, queue_process); atomic_set(&npinfo->refcnt, 1); ops = np->dev->netdev_ops; if (ops->ndo_netpoll_setup) { err = ops->ndo_netpoll_setup(ndev, npinfo); if (err) goto free_npinfo; } } else { npinfo = ndev->npinfo; atomic_inc(&npinfo->refcnt); } npinfo->netpoll = np; if (np->rx_hook) { spin_lock_irqsave(&npinfo->rx_lock, flags); npinfo->rx_flags |= NETPOLL_RX_ENABLED; list_add_tail(&np->rx, &npinfo->rx_np); spin_unlock_irqrestore(&npinfo->rx_lock, flags); } /* last thing to do is link it to the net device structure */ RCU_INIT_POINTER(ndev->npinfo, npinfo); return 0; free_npinfo: kfree(npinfo); out: return err; } EXPORT_SYMBOL_GPL(__netpoll_setup); int netpoll_setup(struct netpoll *np) { struct net_device *ndev = NULL; struct in_device *in_dev; int err; if (np->dev_name) ndev = dev_get_by_name(&init_net, np->dev_name); if (!ndev) { printk(KERN_ERR "%s: %s doesn't exist, aborting.\n", np->name, np->dev_name); return -ENODEV; } if (ndev->master) { printk(KERN_ERR "%s: %s is a slave device, aborting.\n", np->name, np->dev_name); err = -EBUSY; goto put; } if (!netif_running(ndev)) { unsigned long atmost, atleast; printk(KERN_INFO "%s: device %s not up yet, forcing it\n", np->name, np->dev_name); rtnl_lock(); err = dev_open(ndev); rtnl_unlock(); if (err) { printk(KERN_ERR "%s: failed to open %s\n", np->name, ndev->name); goto put; } atleast = jiffies + HZ/10; atmost = jiffies + carrier_timeout * HZ; while (!netif_carrier_ok(ndev)) { if (time_after(jiffies, atmost)) { printk(KERN_NOTICE "%s: timeout waiting for carrier\n", np->name); break; } msleep(1); } /* If carrier appears to come up instantly, we don't * trust it and pause so that we don't pump all our * queued console messages into the bitbucket. */ if (time_before(jiffies, atleast)) { printk(KERN_NOTICE "%s: carrier detect appears" " untrustworthy, waiting 4 seconds\n", np->name); msleep(4000); } } if (!np->local_ip) { rcu_read_lock(); in_dev = __in_dev_get_rcu(ndev); if (!in_dev || !in_dev->ifa_list) { rcu_read_unlock(); printk(KERN_ERR "%s: no IP address for %s, aborting\n", np->name, np->dev_name); err = -EDESTADDRREQ; goto put; } np->local_ip = in_dev->ifa_list->ifa_local; rcu_read_unlock(); printk(KERN_INFO "%s: local IP %pI4\n", np->name, &np->local_ip); } np->dev = ndev; /* fill up the skb queue */ refill_skbs(); rtnl_lock(); err = __netpoll_setup(np); rtnl_unlock(); if (err) goto put; return 0; put: dev_put(ndev); return err; } EXPORT_SYMBOL(netpoll_setup); static int __init netpoll_init(void) { skb_queue_head_init(&skb_pool); return 0; } core_initcall(netpoll_init); void __netpoll_cleanup(struct netpoll *np) { struct netpoll_info *npinfo; unsigned long flags; npinfo = np->dev->npinfo; if (!npinfo) return; if (!list_empty(&npinfo->rx_np)) { spin_lock_irqsave(&npinfo->rx_lock, flags); list_del(&np->rx); if (list_empty(&npinfo->rx_np)) npinfo->rx_flags &= ~NETPOLL_RX_ENABLED; spin_unlock_irqrestore(&npinfo->rx_lock, flags); } if (atomic_dec_and_test(&npinfo->refcnt)) { const struct net_device_ops *ops; ops = np->dev->netdev_ops; if (ops->ndo_netpoll_cleanup) ops->ndo_netpoll_cleanup(np->dev); RCU_INIT_POINTER(np->dev->npinfo, NULL); /* avoid racing with NAPI reading npinfo */ synchronize_rcu_bh(); skb_queue_purge(&npinfo->arp_tx); skb_queue_purge(&npinfo->txq); cancel_delayed_work_sync(&npinfo->tx_work); /* clean after last, unfinished work */ __skb_queue_purge(&npinfo->txq); kfree(npinfo); } } EXPORT_SYMBOL_GPL(__netpoll_cleanup); void netpoll_cleanup(struct netpoll *np) { if (!np->dev) return; rtnl_lock(); __netpoll_cleanup(np); rtnl_unlock(); dev_put(np->dev); np->dev = NULL; } EXPORT_SYMBOL(netpoll_cleanup); int netpoll_trap(void) { return atomic_read(&trapped); } EXPORT_SYMBOL(netpoll_trap); void netpoll_set_trap(int trap) { if (trap) atomic_inc(&trapped); else atomic_dec(&trapped); } EXPORT_SYMBOL(netpoll_set_trap);