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![Daniel Borkmann](/assets/img/avatar_default.png)
As in xmit path we merely update statistics and free the skb, we can mark the device with LLTX feature, so that upper layers can avoid taking the single txq lock on xmit. While at it, also add missing NETIF_F_SG. Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
181 lines
3.9 KiB
C
181 lines
3.9 KiB
C
#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <linux/netlink.h>
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#include <net/net_namespace.h>
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#include <linux/if_arp.h>
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#include <net/rtnetlink.h>
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struct pcpu_lstats {
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u64 packets;
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u64 bytes;
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struct u64_stats_sync syncp;
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};
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static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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int len = skb->len;
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struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
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u64_stats_update_begin(&stats->syncp);
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stats->bytes += len;
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stats->packets++;
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u64_stats_update_end(&stats->syncp);
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dev_kfree_skb(skb);
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return NETDEV_TX_OK;
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}
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static int nlmon_is_valid_mtu(int new_mtu)
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{
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/* Note that in netlink we do not really have an upper limit. On
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* default, we use NLMSG_GOODSIZE. Here at least we should make
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* sure that it's at least the header size.
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*/
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return new_mtu >= (int) sizeof(struct nlmsghdr);
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}
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static int nlmon_change_mtu(struct net_device *dev, int new_mtu)
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{
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if (!nlmon_is_valid_mtu(new_mtu))
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return -EINVAL;
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dev->mtu = new_mtu;
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return 0;
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}
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static int nlmon_dev_init(struct net_device *dev)
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{
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dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
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return dev->lstats == NULL ? -ENOMEM : 0;
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}
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static void nlmon_dev_uninit(struct net_device *dev)
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{
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free_percpu(dev->lstats);
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}
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struct nlmon {
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struct netlink_tap nt;
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};
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static int nlmon_open(struct net_device *dev)
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{
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struct nlmon *nlmon = netdev_priv(dev);
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nlmon->nt.dev = dev;
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nlmon->nt.module = THIS_MODULE;
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return netlink_add_tap(&nlmon->nt);
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}
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static int nlmon_close(struct net_device *dev)
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{
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struct nlmon *nlmon = netdev_priv(dev);
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return netlink_remove_tap(&nlmon->nt);
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}
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static struct rtnl_link_stats64 *
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nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
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{
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int i;
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u64 bytes = 0, packets = 0;
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for_each_possible_cpu(i) {
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const struct pcpu_lstats *nl_stats;
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u64 tbytes, tpackets;
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unsigned int start;
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nl_stats = per_cpu_ptr(dev->lstats, i);
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do {
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start = u64_stats_fetch_begin_irq(&nl_stats->syncp);
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tbytes = nl_stats->bytes;
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tpackets = nl_stats->packets;
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} while (u64_stats_fetch_retry_irq(&nl_stats->syncp, start));
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packets += tpackets;
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bytes += tbytes;
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}
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stats->rx_packets = packets;
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stats->tx_packets = 0;
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stats->rx_bytes = bytes;
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stats->tx_bytes = 0;
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return stats;
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}
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static u32 always_on(struct net_device *dev)
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{
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return 1;
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}
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static const struct ethtool_ops nlmon_ethtool_ops = {
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.get_link = always_on,
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};
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static const struct net_device_ops nlmon_ops = {
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.ndo_init = nlmon_dev_init,
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.ndo_uninit = nlmon_dev_uninit,
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.ndo_open = nlmon_open,
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.ndo_stop = nlmon_close,
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.ndo_start_xmit = nlmon_xmit,
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.ndo_get_stats64 = nlmon_get_stats64,
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.ndo_change_mtu = nlmon_change_mtu,
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};
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static void nlmon_setup(struct net_device *dev)
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{
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dev->type = ARPHRD_NETLINK;
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dev->tx_queue_len = 0;
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dev->netdev_ops = &nlmon_ops;
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dev->ethtool_ops = &nlmon_ethtool_ops;
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dev->destructor = free_netdev;
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dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
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NETIF_F_HIGHDMA | NETIF_F_LLTX;
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dev->flags = IFF_NOARP;
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/* That's rather a softlimit here, which, of course,
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* can be altered. Not a real MTU, but what is to be
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* expected in most cases.
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*/
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dev->mtu = NLMSG_GOODSIZE;
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}
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static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[])
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{
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if (tb[IFLA_ADDRESS])
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return -EINVAL;
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return 0;
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}
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static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
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.kind = "nlmon",
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.priv_size = sizeof(struct nlmon),
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.setup = nlmon_setup,
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.validate = nlmon_validate,
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};
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static __init int nlmon_register(void)
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{
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return rtnl_link_register(&nlmon_link_ops);
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}
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static __exit void nlmon_unregister(void)
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{
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rtnl_link_unregister(&nlmon_link_ops);
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}
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module_init(nlmon_register);
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module_exit(nlmon_unregister);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
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MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
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MODULE_DESCRIPTION("Netlink monitoring device");
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MODULE_ALIAS_RTNL_LINK("nlmon");
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