Hi all,
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.
In previous kernel, When adding a default route, ip6_null_entry will be unlinked from fn->leaf.
So, when deleting a default route, it need to check whether the deleted route is the last one,
if so, ip6_null_entry will link to fn->leaf again.
I am not sure if there is another place unlinks ip6_null_entry from fn->leaf.
Regards,
Gui Jiafeng
From: Gui Jianfeng <[email protected]>
Date: Thu, 27 Dec 2007 15:26:46 +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);
}
But I am not completely convinced that all of these lines
of code can be removed :-)
>> 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);
> }
>
Dave,
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 I am not completely convinced that all of these lines
> of code can be removed :-)
>
>
--
Regards
Gui Jianfeng
--------------------------------------------------
Gui Jianfeng
Development Dept.I
Nanjing Fujitsu Nanda Software Tech. Co., Ltd.(FNST)
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Nanjing, 210029, China
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--------------------------------------------------
From: Gui Jianfeng <[email protected]>
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?
I thought you meant always when the function is called, fn->leaf
cannot ever be NULL.
> From: Gui Jianfeng <[email protected]>
> 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.
>
>
>