Le dimanche 09 janvier 2011 Ã 22:48 +0100, Florian Westphal a Ãcrit :
> broute table init hook sets up the "br_should_route_hook" pointer,
> which then gets called from br_input.
>
> commit a386f99025f13b32502fe5dedf223c20d7283826
> (bridge: add proper RCU annotation to should_route_hook)
> introduced a typedef, and then changed this to:
>
> br_should_route_hook_t *rhook;
> [..]
> rhook = rcu_dereference(br_should_route_hook);
> if (*rhook(skb))
>
> problem is that "br_should_route_hook" contains the address of the function,
> so calling *rhook() results in kernel panic.
>
> Can't simply use "if (rhook(skb)", because br_should_route_hook_t *rhook
> is not a function.
>
> Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
> ---
> Eric, does this patch look sane to you?
>
> Pablo, only the if_bridge.h change is needed.
> If you do not like the br_input.c change, feel
> free to remove it when applying.
>
> Thanks!
>
> diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
> index f7e73c3..dd3f201 100644
> --- a/include/linux/if_bridge.h
> +++ b/include/linux/if_bridge.h
> @@ -103,7 +103,7 @@ struct __fdb_entry {
>
> extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __user *));
>
> -typedef int (*br_should_route_hook_t)(struct sk_buff *skb);
> +typedef int br_should_route_hook_t(struct sk_buff *skb);
> extern br_should_route_hook_t __rcu *br_should_route_hook;
Hi Florian
It seems I was on crack at that time, but I remember having problem with
sparse on :
net/bridge/netfilter/ebtable_broute.c:90:2: error: cannot dereference this type
Lets ignore sparse for the time being...
Please dont change the invocation of (*rhook) to make clear its an
indirect call. Both syntaxes are valid in C.
You also can remove one un needed cast now.
Soemthing like :
diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
index f7e73c3..dd3f201 100644
--- a/include/linux/if_bridge.h
+++ b/include/linux/if_bridge.h
@@ -103,7 +103,7 @@ struct __fdb_entry {
extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __user *));
-typedef int (*br_should_route_hook_t)(struct sk_buff *skb);
+typedef int br_should_route_hook_t(struct sk_buff *skb);
extern br_should_route_hook_t __rcu *br_should_route_hook;
#endif
diff --git a/net/bridge/netfilter/ebtable_broute.c b/net/bridge/netfilter/ebtable_broute.c
index 1bcaf36..ae3f106 100644
--- a/net/bridge/netfilter/ebtable_broute.c
+++ b/net/bridge/netfilter/ebtable_broute.c
@@ -87,8 +87,7 @@ static int __init ebtable_broute_init(void)
if (ret < 0)
return ret;
/* see br_input.c */
- rcu_assign_pointer(br_should_route_hook,
- (br_should_route_hook_t *)ebt_broute);
+ rcu_assign_pointer(br_should_route_hook, ebt_broute);
return 0;
}
Thanks !
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