Hi,
This is a second try to fix the long chain call lengths in netfilter.
The difference with the previous patch is that I got rid of the extra
argument. I somehow didn't see it could be done without using the 'int
*ret2' argument.
A comment on the number of arguments to nf_hook_slow: I don't think the
number of arguments should be decreased. For the bridge-nf code, f.e.,
the indev argument does not equal (*pskb)->dev (this is an answer to a
question of Rusty in the old thread).
A comment on the argument change of nf_hook_slow (sk_buff * to sk_buff
**) and the bad influence on tail call optimization possibilities. From
the discussion in the old thread it became clear that no tail call is
generated for the current code. So, I don't see why this is a reason not
to accept the patch. Furthermore, if gcc ever would become able of doing
the current code with a tail call, it should be very easy to change the
code back to the original. In the meantime, I think this patch is the
best known solution.
cheers,
Bart
--- linux-2.6.11-rc3/include/linux/netfilter.h.old 2005-02-12 13:48:13.000000000 +0100
+++ linux-2.6.11-rc3/include/linux/netfilter.h 2005-02-12 17:02:48.000000000 +0100
@@ -18,7 +18,8 @@
#define NF_STOLEN 2
#define NF_QUEUE 3
#define NF_REPEAT 4
-#define NF_MAX_VERDICT NF_REPEAT
+#define NF_STOP 5
+#define NF_MAX_VERDICT NF_STOP
/* Generic cache responses from hook functions.
<= 0x2000 is used for protocol-flags. */
@@ -138,21 +139,32 @@ void nf_log_packet(int pf,
/* This is gross, but inline doesn't cut it for avoiding the function
call in fast path: gcc doesn't inline (needs value tracking?). --RR */
#ifdef CONFIG_NETFILTER_DEBUG
-#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
- nf_hook_slow((pf), (hook), (skb), (indev), (outdev), (okfn), INT_MIN)
-#define NF_HOOK_THRESH nf_hook_slow
+#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
+({int __ret; \
+if ((__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN)) == 1) \
+ __ret = (okfn)(skb); \
+__ret;})
+#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh) \
+({int __ret; \
+if ((__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh)) == 1) \
+ __ret = (okfn)(skb); \
+__ret;})
#else
-#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
-(list_empty(&nf_hooks[(pf)][(hook)]) \
- ? (okfn)(skb) \
- : nf_hook_slow((pf), (hook), (skb), (indev), (outdev), (okfn), INT_MIN))
-#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh) \
-(list_empty(&nf_hooks[(pf)][(hook)]) \
- ? (okfn)(skb) \
- : nf_hook_slow((pf), (hook), (skb), (indev), (outdev), (okfn), (thresh)))
+#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
+({int __ret; \
+if (list_empty(&nf_hooks[pf][hook]) || \
+ (__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN)) == 1) \
+ __ret = (okfn)(skb); \
+__ret;})
+#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh) \
+({int __ret; \
+if (list_empty(&nf_hooks[pf][hook]) || \
+ (__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh)) == 1) \
+ __ret = (okfn)(skb); \
+__ret;})
#endif
-int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
+int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
struct net_device *indev, struct net_device *outdev,
int (*okfn)(struct sk_buff *), int thresh);
--- linux-2.6.11-rc3/net/core/netfilter.c.old 2005-02-12 13:48:06.000000000 +0100
+++ linux-2.6.11-rc3/net/core/netfilter.c 2005-02-12 16:16:03.000000000 +0100
@@ -349,6 +349,8 @@ static unsigned int nf_iterate(struct li
int (*okfn)(struct sk_buff *),
int hook_thresh)
{
+ unsigned int verdict;
+
/*
* The caller must not block between calls to this
* function because of risk of continuing from deleted element.
@@ -361,28 +363,18 @@ static unsigned int nf_iterate(struct li
/* Optimization: we don't need to hold module
reference here, since function can't sleep. --RR */
- switch (elem->hook(hook, skb, indev, outdev, okfn)) {
- case NF_QUEUE:
- return NF_QUEUE;
-
- case NF_STOLEN:
- return NF_STOLEN;
-
- case NF_DROP:
- return NF_DROP;
-
- case NF_REPEAT:
- *i = (*i)->prev;
- break;
-
+ verdict = elem->hook(hook, skb, indev, outdev, okfn);
+ if (verdict != NF_ACCEPT) {
#ifdef CONFIG_NETFILTER_DEBUG
- case NF_ACCEPT:
- break;
-
- default:
- NFDEBUG("Evil return from %p(%u).\n",
- elem->hook, hook);
+ if (unlikely(verdict > NF_MAX_VERDICT)) {
+ NFDEBUG("Evil return from %p(%u).\n",
+ elem->hook, hook);
+ continue;
+ }
#endif
+ if (verdict != NF_REPEAT)
+ return verdict;
+ *i = (*i)->prev;
}
}
return NF_ACCEPT;
@@ -494,7 +486,9 @@ static int nf_queue(struct sk_buff *skb,
return 1;
}
-int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
+/* Returns 1 if okfn() needs to be executed by the caller,
+ * -EPERM for NF_DROP, 0 otherwise. */
+int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
struct net_device *indev,
struct net_device *outdev,
int (*okfn)(struct sk_buff *),
@@ -508,34 +502,29 @@ int nf_hook_slow(int pf, unsigned int ho
rcu_read_lock();
#ifdef CONFIG_NETFILTER_DEBUG
- if (skb->nf_debug & (1 << hook)) {
+ if (unlikely((*pskb)->nf_debug & (1 << hook))) {
printk("nf_hook: hook %i already set.\n", hook);
- nf_dump_skb(pf, skb);
+ nf_dump_skb(pf, *pskb);
}
- skb->nf_debug |= (1 << hook);
+ (*pskb)->nf_debug |= (1 << hook);
#endif
elem = &nf_hooks[pf][hook];
- next_hook:
- verdict = nf_iterate(&nf_hooks[pf][hook], &skb, hook, indev,
+next_hook:
+ verdict = nf_iterate(&nf_hooks[pf][hook], pskb, hook, indev,
outdev, &elem, okfn, hook_thresh);
- if (verdict == NF_QUEUE) {
+ if (verdict == NF_ACCEPT || verdict == NF_STOP) {
+ ret = 1;
+ goto unlock;
+ } else if (verdict == NF_DROP) {
+ kfree_skb(*pskb);
+ ret = -EPERM;
+ } else if (verdict == NF_QUEUE) {
NFDEBUG("nf_hook: Verdict = QUEUE.\n");
- if (!nf_queue(skb, elem, pf, hook, indev, outdev, okfn))
+ if (!nf_queue(*pskb, elem, pf, hook, indev, outdev, okfn))
goto next_hook;
}
-
- switch (verdict) {
- case NF_ACCEPT:
- ret = okfn(skb);
- break;
-
- case NF_DROP:
- kfree_skb(skb);
- ret = -EPERM;
- break;
- }
-
+unlock:
rcu_read_unlock();
return ret;
}
--- linux-2.6.11-rc3/net/bridge/br_netfilter.c.old 2005-02-12 13:48:22.000000000 +0100
+++ linux-2.6.11-rc3/net/bridge/br_netfilter.c 2005-02-12 17:04:45.000000000 +0100
@@ -829,8 +829,7 @@ static unsigned int ip_sabotage_in(unsig
{
if ((*pskb)->nf_bridge &&
!((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
- okfn(*pskb);
- return NF_STOLEN;
+ return NF_STOP;
}
return NF_ACCEPT;
@@ -891,8 +890,7 @@ static unsigned int ip_sabotage_out(unsi
if (out->priv_flags & IFF_802_1Q_VLAN)
nf_bridge->netoutdev = (struct net_device *)out;
#endif
- okfn(skb);
- return NF_STOLEN;
+ return NF_STOP;
}
return NF_ACCEPT;
