On Wed, Nov 4, 2009 at 2:04 AM, Jan Engelhardt <jengelh@xxxxxxxxxx> wrote:
>
> -#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) \
> -({int __ret; \
> -if ((cond) || (__ret = nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN)) == 1)\
> - __ret = (okfn)(skb); \
> -__ret;})
This code isn't the same as the linus tree's. And has a risk about
uninitialized variable __ret.
#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) \
({int __ret; \
if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn,
INT_MIN, cond)) == 1)\
__ret = (okfn)(skb); \
__ret;})
/**
* nf_hook_thresh - call a netfilter hook
*
* Returns 1 if the hook has allowed the packet to pass. The function
* okfn must be invoked by the caller in this case. Any other return
* value indicates the packet has been consumed by the hook.
*/
static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
struct sk_buff *skb,
struct net_device *indev,
struct net_device *outdev,
int (*okfn)(struct sk_buff *), int thresh,
int cond)
{
if (!cond)
return 1;
#ifndef CONFIG_NETFILTER_DEBUG
if (list_empty(&nf_hooks[pf][hook]))
return 1;
#endif
return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
}
> +static inline int
> +NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
> + struct net_device *in, struct net_device *out,
> + int (*okfn)(struct sk_buff *), bool cond)
> +{
> + int ret = 1;
> + if (cond ||
> + (ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN) == 1))
> + ret = okfn(skb);
> + return ret;
> +}
The fact is: no matter the cond value, okfn(skb) should always be
called, and hf_hook_thresh() should be called only when cond is true.
So the code will be.
if (cond) {
if (ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1)
ret = okfn(skb);
} else {
ret = okfn(skb);
}
--
Regards，
Changli Gao(xiaosuo@xxxxxxxxx)
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