Re: do_IRQ: stack overflow: 872..

From
Bart De Schuymer <hidden>
Date
2005-01-07 21:27:21
Also in
bridge
Reply to
Stephen Hemminger, 2005-01-07
Op vr, 07-01-2005 te 10:00 -0800, schreef Stephen Hemminger:
On Fri, 07 Jan 2005 17:05:59 +0000
David Woodhouse [off-list ref] wrote:
quoted
I don't think it's recursing -- I think the stack trace is just a bit
noisy. The problem is that the bridge code, especially with br_netfilter
in the equation, is implicated in code paths which are just _too_ deep.
This happens when you're bridging packets received in an interrupt while
you were deep in journalling code, and it's also been seen with a call
trace something like nfs->sunrpc->ip->bridge->br_netfilter.
Sounds like an argument for interrupt stacks.
quoted
One option might be to make br_dev_xmit() just queue the packet rather
than trying to deliver it to all the slave devices immediately. Then the
actual retransmission can be handled from a context where we're _not_
short of stack; perhaps from a dedicated kernel thread. 
Probably the solution would be to handle it in the filter code
that way if we are not filtering, we can use the interrupt path,
but if filtering just defer to a safer context (like soft irq).
How about something like the patch below (untested but compiles)?
The current netfilter scheme adds one function call to the call chain
for each NF_HOOK and NF_HOOK_THRESH. This can be prevented by executing
the okfn in the calling function instead of in nf_hook_slow().
I didn't check if there's any code that actually uses the return value
from NF_HOOK. If so, this patch won't work well in its current form as -
EPERM is now also returned for NF_QUEUE and NF_STOLEN.

Another 2 calls of okfn can be postponed in br_netfilter.c by adding
NF_STOP, which would work like NF_STOLEN except that okfn is still
called. But I'd first like to get the IPv4/IPv6 fix for br_netfilter.c
accepted (see another thread on netdev).

cheers,
Bart

--- linux-2.6.10/include/linux/netfilter.h.old	2005-01-07 20:41:30.000000000 +0100
+++ linux-2.6.10/include/linux/netfilter.h	2005-01-07 22:04:57.096626176 +0100
@@ -138,21 +138,32 @@ 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 = nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN); \
+if (!__ret)								    \
+	__ret = (okfn)(skb);						    \
+__ret;})
+#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)	    \
+({int __ret = nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh);  \
+if (!__ret)								    \
+	__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 = 0;							     \
+if (list_empty(&nf_hooks[pf][hook]) ||					     \
+    !(__ret = nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN))) \
+	__ret = (okfn)(skb);						     \
+__ret;})
+#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)	     \
+({int __ret = 0;							     \
+if (list_empty(&nf_hooks[pf][hook]) ||					     \
+    !(__ret = nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh)))  \
+	__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-2.6.10/net/core/netfilter.c.old	2005-01-07 20:41:47.000000000 +0100
+++ linux-2.6.10/net/core/netfilter.c	2005-01-07 21:52:13.659686232 +0100
@@ -494,7 +494,7 @@ static int nf_queue(struct sk_buff *skb,
 	return 1;
 }
 
-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 *),
@@ -508,30 +508,28 @@ int nf_hook_slow(int pf, unsigned int ho
 	rcu_read_lock();
 
 #ifdef CONFIG_NETFILTER_DEBUG
-	if (skb->nf_debug & (1 << hook)) {
+	if ((*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);
 #endif
 
 	elem = &nf_hooks[pf][hook];
  next_hook:
-	verdict = nf_iterate(&nf_hooks[pf][hook], &skb, hook, indev,
+	verdict = nf_iterate(&nf_hooks[pf][hook], pskb, hook, indev,
 			     outdev, &elem, okfn, hook_thresh);
 	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);
+		kfree_skb(*pskb);
+	case NF_STOLEN:
+	case NF_QUEUE:
 		ret = -EPERM;
 		break;
 	}
Thread (30 messages) 30 messages, 9 authors, last reply 2005-01-28
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