linux/net/sched/act_gact.c

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/*
* net/sched/act_gact.c Generic actions
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* copyright Jamal Hadi Salim (2002-4)
*
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/module.h>
#include <linux/init.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <linux/tc_act/tc_gact.h>
#include <net/tc_act/tc_gact.h>
#define GACT_TAB_MASK 15
netns: make struct pernet_operations::id unsigned int 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>
2016-11-17 09:58:21 +08:00
static unsigned int gact_net_id;
static struct tc_action_ops act_gact_ops;
#ifdef CONFIG_GACT_PROB
static int gact_net_rand(struct tcf_gact *gact)
{
smp_rmb(); /* coupled with smp_wmb() in tcf_gact_init() */
if (prandom_u32() % gact->tcfg_pval)
return gact->tcf_action;
return gact->tcfg_paction;
}
static int gact_determ(struct tcf_gact *gact)
{
u32 pack = atomic_inc_return(&gact->packets);
smp_rmb(); /* coupled with smp_wmb() in tcf_gact_init() */
if (pack % gact->tcfg_pval)
return gact->tcf_action;
return gact->tcfg_paction;
}
typedef int (*g_rand)(struct tcf_gact *gact);
static g_rand gact_rand[MAX_RAND] = { NULL, gact_net_rand, gact_determ };
#endif /* CONFIG_GACT_PROB */
static const struct nla_policy gact_policy[TCA_GACT_MAX + 1] = {
[TCA_GACT_PARMS] = { .len = sizeof(struct tc_gact) },
[TCA_GACT_PROB] = { .len = sizeof(struct tc_gact_p) },
};
static int tcf_gact_init(struct net *net, struct nlattr *nla,
struct nlattr *est, struct tc_action **a,
int ovr, int bind)
{
struct tc_action_net *tn = net_generic(net, gact_net_id);
struct nlattr *tb[TCA_GACT_MAX + 1];
struct tc_gact *parm;
struct tcf_gact *gact;
int ret = 0;
int err;
#ifdef CONFIG_GACT_PROB
struct tc_gact_p *p_parm = NULL;
#endif
if (nla == NULL)
return -EINVAL;
err = nla_parse_nested(tb, TCA_GACT_MAX, nla, gact_policy);
if (err < 0)
return err;
if (tb[TCA_GACT_PARMS] == NULL)
return -EINVAL;
parm = nla_data(tb[TCA_GACT_PARMS]);
#ifndef CONFIG_GACT_PROB
if (tb[TCA_GACT_PROB] != NULL)
return -EOPNOTSUPP;
#else
if (tb[TCA_GACT_PROB]) {
p_parm = nla_data(tb[TCA_GACT_PROB]);
if (p_parm->ptype >= MAX_RAND)
return -EINVAL;
}
#endif
if (!tcf_hash_check(tn, parm->index, a, bind)) {
ret = tcf_hash_create(tn, parm->index, est, a,
&act_gact_ops, bind, true);
if (ret)
return ret;
ret = ACT_P_CREATED;
} else {
if (bind)/* dont override defaults */
return 0;
tcf_hash_release(*a, bind);
if (!ovr)
return -EEXIST;
}
gact = to_gact(*a);
ASSERT_RTNL();
gact->tcf_action = parm->action;
#ifdef CONFIG_GACT_PROB
if (p_parm) {
gact->tcfg_paction = p_parm->paction;
gact->tcfg_pval = max_t(u16, 1, p_parm->pval);
/* Make sure tcfg_pval is written before tcfg_ptype
* coupled with smp_rmb() in gact_net_rand() & gact_determ()
*/
smp_wmb();
gact->tcfg_ptype = p_parm->ptype;
}
#endif
if (ret == ACT_P_CREATED)
tcf_hash_insert(tn, *a);
return ret;
}
static int tcf_gact(struct sk_buff *skb, const struct tc_action *a,
struct tcf_result *res)
{
struct tcf_gact *gact = to_gact(a);
int action = READ_ONCE(gact->tcf_action);
#ifdef CONFIG_GACT_PROB
{
u32 ptype = READ_ONCE(gact->tcfg_ptype);
if (ptype)
action = gact_rand[ptype](gact);
}
#endif
bstats_cpu_update(this_cpu_ptr(gact->common.cpu_bstats), skb);
if (action == TC_ACT_SHOT)
qstats_drop_inc(this_cpu_ptr(gact->common.cpu_qstats));
tcf_lastuse_update(&gact->tcf_tm);
return action;
}
static void tcf_gact_stats_update(struct tc_action *a, u64 bytes, u32 packets,
u64 lastuse)
{
struct tcf_gact *gact = to_gact(a);
int action = READ_ONCE(gact->tcf_action);
struct tcf_t *tm = &gact->tcf_tm;
_bstats_cpu_update(this_cpu_ptr(gact->common.cpu_bstats), bytes,
packets);
if (action == TC_ACT_SHOT)
this_cpu_ptr(gact->common.cpu_qstats)->drops += packets;
tm->lastuse = lastuse;
}
static int tcf_gact_dump(struct sk_buff *skb, struct tc_action *a,
int bind, int ref)
{
unsigned char *b = skb_tail_pointer(skb);
struct tcf_gact *gact = to_gact(a);
struct tc_gact opt = {
.index = gact->tcf_index,
.refcnt = gact->tcf_refcnt - ref,
.bindcnt = gact->tcf_bindcnt - bind,
.action = gact->tcf_action,
};
struct tcf_t t;
if (nla_put(skb, TCA_GACT_PARMS, sizeof(opt), &opt))
goto nla_put_failure;
#ifdef CONFIG_GACT_PROB
if (gact->tcfg_ptype) {
struct tc_gact_p p_opt = {
.paction = gact->tcfg_paction,
.pval = gact->tcfg_pval,
.ptype = gact->tcfg_ptype,
};
if (nla_put(skb, TCA_GACT_PROB, sizeof(p_opt), &p_opt))
goto nla_put_failure;
}
#endif
tcf_tm_dump(&t, &gact->tcf_tm);
if (nla_put_64bit(skb, TCA_GACT_TM, sizeof(t), &t, TCA_GACT_PAD))
goto nla_put_failure;
return skb->len;
nla_put_failure:
nlmsg_trim(skb, b);
return -1;
}
static int tcf_gact_walker(struct net *net, struct sk_buff *skb,
struct netlink_callback *cb, int type,
const struct tc_action_ops *ops)
{
struct tc_action_net *tn = net_generic(net, gact_net_id);
return tcf_generic_walker(tn, skb, cb, type, ops);
}
static int tcf_gact_search(struct net *net, struct tc_action **a, u32 index)
{
struct tc_action_net *tn = net_generic(net, gact_net_id);
return tcf_hash_search(tn, a, index);
}
static struct tc_action_ops act_gact_ops = {
.kind = "gact",
.type = TCA_ACT_GACT,
.owner = THIS_MODULE,
.act = tcf_gact,
.stats_update = tcf_gact_stats_update,
.dump = tcf_gact_dump,
.init = tcf_gact_init,
.walk = tcf_gact_walker,
.lookup = tcf_gact_search,
.size = sizeof(struct tcf_gact),
};
static __net_init int gact_init_net(struct net *net)
{
struct tc_action_net *tn = net_generic(net, gact_net_id);
return tc_action_net_init(tn, &act_gact_ops, GACT_TAB_MASK);
}
static void __net_exit gact_exit_net(struct net *net)
{
struct tc_action_net *tn = net_generic(net, gact_net_id);
tc_action_net_exit(tn);
}
static struct pernet_operations gact_net_ops = {
.init = gact_init_net,
.exit = gact_exit_net,
.id = &gact_net_id,
.size = sizeof(struct tc_action_net),
};
MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
MODULE_DESCRIPTION("Generic Classifier actions");
MODULE_LICENSE("GPL");
static int __init gact_init_module(void)
{
#ifdef CONFIG_GACT_PROB
pr_info("GACT probability on\n");
#else
pr_info("GACT probability NOT on\n");
#endif
return tcf_register_action(&act_gact_ops, &gact_net_ops);
}
static void __exit gact_cleanup_module(void)
{
tcf_unregister_action(&act_gact_ops, &gact_net_ops);
}
module_init(gact_init_module);
module_exit(gact_cleanup_module);