![Alexey Dobriyan](/assets/img/avatar_default.png)
Make struct pernet_operations::id unsigned. There are 2 reasons to do so: 1) This field is really an index into an zero based array and thus is unsigned entity. Using negative value is out-of-bound access by definition. 2) On x86_64 unsigned 32-bit data which are mixed with pointers via array indexing or offsets added or subtracted to pointers are preffered to signed 32-bit data. "int" being used as an array index needs to be sign-extended to 64-bit before being used. void f(long *p, int i) { g(p[i]); } roughly translates to movsx rsi, esi mov rdi, [rsi+...] call g MOVSX is 3 byte instruction which isn't necessary if the variable is unsigned because x86_64 is zero extending by default. Now, there is net_generic() function which, you guessed it right, uses "int" as an array index: static inline void *net_generic(const struct net *net, int id) { ... ptr = ng->ptr[id - 1]; ... } And this function is used a lot, so those sign extensions add up. Patch snipes ~1730 bytes on allyesconfig kernel (without all junk messing with code generation): add/remove: 0/0 grow/shrink: 70/598 up/down: 396/-2126 (-1730) Unfortunately some functions actually grow bigger. This is a semmingly random artefact of code generation with register allocator being used differently. gcc decides that some variable needs to live in new r8+ registers and every access now requires REX prefix. Or it is shifted into r12, so [r12+0] addressing mode has to be used which is longer than [r8] However, overall balance is in negative direction: add/remove: 0/0 grow/shrink: 70/598 up/down: 396/-2126 (-1730) function old new delta nfsd4_lock 3886 3959 +73 tipc_link_build_proto_msg 1096 1140 +44 mac80211_hwsim_new_radio 2776 2808 +32 tipc_mon_rcv 1032 1058 +26 svcauth_gss_legacy_init 1413 1429 +16 tipc_bcbase_select_primary 379 392 +13 nfsd4_exchange_id 1247 1260 +13 nfsd4_setclientid_confirm 782 793 +11 ... put_client_renew_locked 494 480 -14 ip_set_sockfn_get 730 716 -14 geneve_sock_add 829 813 -16 nfsd4_sequence_done 721 703 -18 nlmclnt_lookup_host 708 686 -22 nfsd4_lockt 1085 1063 -22 nfs_get_client 1077 1050 -27 tcf_bpf_init 1106 1076 -30 nfsd4_encode_fattr 5997 5930 -67 Total: Before=154856051, After=154854321, chg -0.00% Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
240 lines
5.9 KiB
C
240 lines
5.9 KiB
C
/*
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* net/sched/act_connmark.c netfilter connmark retriever action
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* skb mark is over-written
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*
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* Copyright (c) 2011 Felix Fietkau <nbd@openwrt.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/rtnetlink.h>
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#include <linux/pkt_cls.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <net/netlink.h>
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#include <net/pkt_sched.h>
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#include <net/act_api.h>
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#include <uapi/linux/tc_act/tc_connmark.h>
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#include <net/tc_act/tc_connmark.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_core.h>
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#include <net/netfilter/nf_conntrack_zones.h>
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#define CONNMARK_TAB_MASK 3
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static unsigned int connmark_net_id;
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static struct tc_action_ops act_connmark_ops;
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static int tcf_connmark(struct sk_buff *skb, const struct tc_action *a,
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struct tcf_result *res)
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{
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const struct nf_conntrack_tuple_hash *thash;
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struct nf_conntrack_tuple tuple;
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enum ip_conntrack_info ctinfo;
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struct tcf_connmark_info *ca = to_connmark(a);
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struct nf_conntrack_zone zone;
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struct nf_conn *c;
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int proto;
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spin_lock(&ca->tcf_lock);
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tcf_lastuse_update(&ca->tcf_tm);
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bstats_update(&ca->tcf_bstats, skb);
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if (skb->protocol == htons(ETH_P_IP)) {
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if (skb->len < sizeof(struct iphdr))
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goto out;
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proto = NFPROTO_IPV4;
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} else if (skb->protocol == htons(ETH_P_IPV6)) {
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if (skb->len < sizeof(struct ipv6hdr))
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goto out;
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proto = NFPROTO_IPV6;
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} else {
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goto out;
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}
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c = nf_ct_get(skb, &ctinfo);
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if (c) {
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skb->mark = c->mark;
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/* using overlimits stats to count how many packets marked */
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ca->tcf_qstats.overlimits++;
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goto out;
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}
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if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb),
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proto, ca->net, &tuple))
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goto out;
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zone.id = ca->zone;
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zone.dir = NF_CT_DEFAULT_ZONE_DIR;
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thash = nf_conntrack_find_get(ca->net, &zone, &tuple);
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if (!thash)
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goto out;
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c = nf_ct_tuplehash_to_ctrack(thash);
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/* using overlimits stats to count how many packets marked */
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ca->tcf_qstats.overlimits++;
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skb->mark = c->mark;
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nf_ct_put(c);
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out:
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spin_unlock(&ca->tcf_lock);
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return ca->tcf_action;
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}
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static const struct nla_policy connmark_policy[TCA_CONNMARK_MAX + 1] = {
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[TCA_CONNMARK_PARMS] = { .len = sizeof(struct tc_connmark) },
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};
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static int tcf_connmark_init(struct net *net, struct nlattr *nla,
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struct nlattr *est, struct tc_action **a,
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int ovr, int bind)
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{
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struct tc_action_net *tn = net_generic(net, connmark_net_id);
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struct nlattr *tb[TCA_CONNMARK_MAX + 1];
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struct tcf_connmark_info *ci;
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struct tc_connmark *parm;
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int ret = 0;
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if (!nla)
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return -EINVAL;
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ret = nla_parse_nested(tb, TCA_CONNMARK_MAX, nla, connmark_policy);
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if (ret < 0)
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return ret;
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parm = nla_data(tb[TCA_CONNMARK_PARMS]);
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if (!tcf_hash_check(tn, parm->index, a, bind)) {
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ret = tcf_hash_create(tn, parm->index, est, a,
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&act_connmark_ops, bind, false);
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if (ret)
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return ret;
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ci = to_connmark(*a);
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ci->tcf_action = parm->action;
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ci->net = net;
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ci->zone = parm->zone;
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tcf_hash_insert(tn, *a);
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ret = ACT_P_CREATED;
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} else {
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ci = to_connmark(*a);
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if (bind)
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return 0;
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tcf_hash_release(*a, bind);
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if (!ovr)
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return -EEXIST;
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/* replacing action and zone */
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ci->tcf_action = parm->action;
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ci->zone = parm->zone;
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}
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return ret;
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}
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static inline int tcf_connmark_dump(struct sk_buff *skb, struct tc_action *a,
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int bind, int ref)
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{
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unsigned char *b = skb_tail_pointer(skb);
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struct tcf_connmark_info *ci = to_connmark(a);
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struct tc_connmark opt = {
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.index = ci->tcf_index,
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.refcnt = ci->tcf_refcnt - ref,
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.bindcnt = ci->tcf_bindcnt - bind,
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.action = ci->tcf_action,
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.zone = ci->zone,
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};
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struct tcf_t t;
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if (nla_put(skb, TCA_CONNMARK_PARMS, sizeof(opt), &opt))
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goto nla_put_failure;
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tcf_tm_dump(&t, &ci->tcf_tm);
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if (nla_put_64bit(skb, TCA_CONNMARK_TM, sizeof(t), &t,
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TCA_CONNMARK_PAD))
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goto nla_put_failure;
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return skb->len;
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nla_put_failure:
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nlmsg_trim(skb, b);
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return -1;
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}
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static int tcf_connmark_walker(struct net *net, struct sk_buff *skb,
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struct netlink_callback *cb, int type,
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const struct tc_action_ops *ops)
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{
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struct tc_action_net *tn = net_generic(net, connmark_net_id);
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return tcf_generic_walker(tn, skb, cb, type, ops);
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}
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static int tcf_connmark_search(struct net *net, struct tc_action **a, u32 index)
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{
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struct tc_action_net *tn = net_generic(net, connmark_net_id);
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return tcf_hash_search(tn, a, index);
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}
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static struct tc_action_ops act_connmark_ops = {
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.kind = "connmark",
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.type = TCA_ACT_CONNMARK,
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.owner = THIS_MODULE,
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.act = tcf_connmark,
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.dump = tcf_connmark_dump,
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.init = tcf_connmark_init,
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.walk = tcf_connmark_walker,
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.lookup = tcf_connmark_search,
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.size = sizeof(struct tcf_connmark_info),
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};
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static __net_init int connmark_init_net(struct net *net)
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{
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struct tc_action_net *tn = net_generic(net, connmark_net_id);
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return tc_action_net_init(tn, &act_connmark_ops, CONNMARK_TAB_MASK);
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}
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static void __net_exit connmark_exit_net(struct net *net)
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{
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struct tc_action_net *tn = net_generic(net, connmark_net_id);
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tc_action_net_exit(tn);
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}
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static struct pernet_operations connmark_net_ops = {
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.init = connmark_init_net,
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.exit = connmark_exit_net,
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.id = &connmark_net_id,
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.size = sizeof(struct tc_action_net),
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};
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static int __init connmark_init_module(void)
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{
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return tcf_register_action(&act_connmark_ops, &connmark_net_ops);
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}
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static void __exit connmark_cleanup_module(void)
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{
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tcf_unregister_action(&act_connmark_ops, &connmark_net_ops);
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}
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module_init(connmark_init_module);
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module_exit(connmark_cleanup_module);
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MODULE_AUTHOR("Felix Fietkau <nbd@openwrt.org>");
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MODULE_DESCRIPTION("Connection tracking mark restoring");
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MODULE_LICENSE("GPL");
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