linux-kernel - Re: fib6_del_route has redundant code

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Message-ID: <4774B30B.3080507@cn.fujitsu.com>
Date:	Fri, 28 Dec 2007 16:25:47 +0800
From:	Gui Jianfeng <guijianfeng@...fujitsu.com>
To:	David Miller <davem@...emloft.net>
CC:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: fib6_del_route has redundant code

> From: Gui Jianfeng <guijianfeng@...fujitsu.com>
> Date: Fri, 28 Dec 2007 13:58:21 +0800
> 
>>>> I think the following code in fib6_del_route in the latest kernel is useless.
>>>> 1125         if (fn->leaf == NULL && fn->fn_flags&RTN_TL_ROOT)
>>>> 1126                 fn->leaf = &ip6_null_entry;
>>>>
>>>> ip6_null_entry will never be unlinked from fn->leaf now, that is,
>>>> fn->leaf == NULL will never meet.
>>> I think you are right, but if it is true the next block of
>>> code is dead too:
>>>
>>> 	/* If it was last route, expunge its radix tree node */
>>> 	if (fn->leaf == NULL) {
>>> 		fn->fn_flags &= ~RTN_RTINFO;
>>> 		rt6_stats.fib_route_nodes--;
>>> 		fn = fib6_repair_tree(fn);
>>> 	}
>>>
>> I think this block of code can't be removed, because just the
>> root(default route) fn->leaf always has ip6_null_entry on it. The
>> normal fn->leaf becomes NULL when last route has been deleted, the
>> radix tree should be expunged.
> 
> But you said (still quoted above) that fn->leaf == NULL will not
> occur.
> 
> Do you mean this, only in the case that the RTN_TL_ROOT flag is set?
  yes, I mean this :-)

> 
> I thought you meant always when the function is called, fn->leaf
> cannot ever be NULL.
  its my fault, sorry for the inconvenient.

> 
> 
> 
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