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netfilter: replace list_head with single linked list

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The netfilter hook list never uses the prev pointer, and so can be trimmed to
be a simple singly-linked list.

In addition to having a more light weight structure for hook traversal,
struct net becomes 5568 bytes (down from 6400) and struct net_device becomes
2176 bytes (down from 2240).

Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Aaron Conole
2016-09-21 11:35:07 -04:00
committed by Pablo Neira Ayuso
parent 54f17bbc52
commit e3b37f11e6
10 changed files with 169 additions and 118 deletions
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63
include/linux/netfilter.h
View File

@@ -55,12 +55,34 @@ struct nf_hook_state {
struct net_device *out;
struct sock *sk;
struct net *net;
struct list_head *hook_list;
struct nf_hook_entry __rcu *hook_entries;
int (*okfn)(struct net *, struct sock *, struct sk_buff *);
};
typedef unsigned int nf_hookfn(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state);
struct nf_hook_ops {
struct list_head list;
/* User fills in from here down. */
nf_hookfn *hook;
struct net_device *dev;
void *priv;
u_int8_t pf;
unsigned int hooknum;
/* Hooks are ordered in ascending priority. */
int priority;
};
struct nf_hook_entry {
struct nf_hook_entry __rcu *next;
struct nf_hook_ops ops;
const struct nf_hook_ops *orig_ops;
};
static inline void nf_hook_state_init(struct nf_hook_state *p,
struct list_head *hook_list,
struct nf_hook_entry *hook_entry,
unsigned int hook,
int thresh, u_int8_t pf,
struct net_device *indev,
@@ -76,26 +98,11 @@ static inline void nf_hook_state_init(struct nf_hook_state *p,
p->out = outdev;
p->sk = sk;
p->net = net;
p->hook_list = hook_list;
RCU_INIT_POINTER(p->hook_entries, hook_entry);
p->okfn = okfn;
}
typedef unsigned int nf_hookfn(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state);
struct nf_hook_ops {
struct list_head list;
/* User fills in from here down. */
nf_hookfn *hook;
struct net_device *dev;
void *priv;
u_int8_t pf;
unsigned int hooknum;
/* Hooks are ordered in ascending priority. */
int priority;
};
struct nf_sockopt_ops {
struct list_head list;
@@ -161,7 +168,8 @@ static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
int (*okfn)(struct net *, struct sock *, struct sk_buff *),
int thresh)
{
struct list_head *hook_list;
struct nf_hook_entry *hook_head;
int ret = 1;
#ifdef HAVE_JUMP_LABEL
if (__builtin_constant_p(pf) &&
@@ -170,22 +178,19 @@ static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
return 1;
#endif
hook_list = &net->nf.hooks[pf][hook];
if (!list_empty(hook_list)) {
rcu_read_lock();
hook_head = rcu_dereference(net->nf.hooks[pf][hook]);
if (hook_head) {
struct nf_hook_state state;
int ret;
/* We may already have this, but read-locks nest anyway */
rcu_read_lock();
nf_hook_state_init(&state, hook_list, hook, thresh,
nf_hook_state_init(&state, hook_head, hook, thresh,
pf, indev, outdev, sk, net, okfn);
ret = nf_hook_slow(skb, &state);
rcu_read_unlock();
return ret;
}
return 1;
rcu_read_unlock();
return ret;
}
static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,