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Message-ID: <dd9aefd4-b436-4ef7-8d1f-e966bccb2a14@gmail.com>
Date: Thu, 7 Dec 2023 11:08:22 -0800
From: Kui-Feng Lee <sinquersw@...il.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: David Ahern <dsahern@...nel.org>, patchwork-bot+netdevbpf@...nel.org,
Kui-Feng Lee <thinker.li@...il.com>, davem@...emloft.net, kuba@...nel.org,
pabeni@...hat.com, netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH net-next] ipv6: add debug checks in fib6_info_release()
On 12/7/23 11:05, Eric Dumazet wrote:
> On Thu, Dec 7, 2023 at 8:00 PM Kui-Feng Lee <sinquersw@...il.com> wrote:
>>
>>
>>
>> On 12/7/23 10:40, Kui-Feng Lee wrote:
>>>
>>>
>>> On 12/7/23 10:36, Kui-Feng Lee wrote:
>>>>
>>>>
>>>> On 12/7/23 10:25, David Ahern wrote:
>>>>> On 12/7/23 11:22 AM, Eric Dumazet wrote:
>>>>>> Feel free to amend the patch, but the issue is that we insert a fib
>>>>>> gc_link to a list, then free the fi6 object without removing it first
>>>>>> from the external list.
>>>>>
>>>>> yes, move the insert down:
>>>>>
>>>>> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
>>>>> index b132feae3393..7257ba0e72b7 100644
>>>>> --- a/net/ipv6/route.c
>>>>> +++ b/net/ipv6/route.c
>>>>> @@ -3762,12 +3762,6 @@ static struct fib6_info
>>>>> *ip6_route_info_create(struct fib6_config *cfg,
>>>>> if (cfg->fc_flags & RTF_ADDRCONF)
>>>>> rt->dst_nocount = true;
>>>>>
>>>>> - if (cfg->fc_flags & RTF_EXPIRES)
>>>>> - fib6_set_expires_locked(rt, jiffies +
>>>>> -
>>>>> clock_t_to_jiffies(cfg->fc_expires));
>>>>> - else
>>>>> - fib6_clean_expires_locked(rt);
>>>>> -
>>>>
>>>> fib6_set_expires_locked() here actually doesn't insert a fib gc_link
>>>> since rt->fib6_table is not assigned yet. The gc_link will
>>>> be inserted by fib6_add() being called later.
>>>>
>>>>
>>>>> if (cfg->fc_protocol == RTPROT_UNSPEC)
>>>>> cfg->fc_protocol = RTPROT_BOOT;
>>>>> rt->fib6_protocol = cfg->fc_protocol;
>>>>> @@ -3824,6 +3818,12 @@ static struct fib6_info
>>>>> *ip6_route_info_create(struct fib6_config *cfg,
>>>>> } else
>>>>> rt->fib6_prefsrc.plen = 0;
>>>>>
>>>>> +
>>>>> + if (cfg->fc_flags & RTF_EXPIRES)
>>>>> + fib6_set_expires_locked(rt, jiffies +
>>>>> +
>>>>> clock_t_to_jiffies(cfg->fc_expires));
>>>>> + else
>>>>> + fib6_clean_expires_locked(rt);
>>>>> return rt;
>>>>> out:
>>>>> fib6_info_release(rt);
>>>>
>>>> However, this should fix the warning messages.
>>> Just realize this cause inserting the gc_link twice. fib6_add()
>>> will try to add it again!
>>
>> I made a minor change to the patch that fix warning messages
>> provided by David Ahern. Will send an official patch later.
>>
>> --- a/net/ipv6/route.c
>> +++ b/net/ipv6/route.c
>> @@ -3762,17 +3762,10 @@ static struct fib6_info
>> *ip6_route_info_create(struct fib6_config *cfg,
>> if (cfg->fc_flags & RTF_ADDRCONF)
>> rt->dst_nocount = true;
>>
>> - if (cfg->fc_flags & RTF_EXPIRES)
>> - fib6_set_expires_locked(rt, jiffies +
>> -
>> clock_t_to_jiffies(cfg->fc_expires));
>> - else
>> - fib6_clean_expires_locked(rt);
>> -
>> if (cfg->fc_protocol == RTPROT_UNSPEC)
>> cfg->fc_protocol = RTPROT_BOOT;
>> rt->fib6_protocol = cfg->fc_protocol;
>>
>> - rt->fib6_table = table;
>> rt->fib6_metric = cfg->fc_metric;
>> rt->fib6_type = cfg->fc_type ? : RTN_UNICAST;
>> rt->fib6_flags = cfg->fc_flags & ~RTF_GATEWAY;
>> @@ -3824,6 +3817,17 @@ static struct fib6_info
>> *ip6_route_info_create(struct fib6_config *cfg,
>> } else
>> rt->fib6_prefsrc.plen = 0;
>>
>> + if (cfg->fc_flags & RTF_EXPIRES)
>> + fib6_set_expires_locked(rt, jiffies +
>> +
>> clock_t_to_jiffies(cfg->fc_expires));
>> + else
>> + fib6_clean_expires_locked(rt);
>
> Note that I do not see why we call fib6_clean_expires_locked() on a
> freshly allocated object.
>
> f6i->expires should already be zero...
>
Agree! I will remove it as well.
>> + /* Set fib6_table after fib6_set_expires_locked() to ensure the
>> + * gc_link is not inserted until fib6_add() is called to insert the
>> + * fib6_info to the fib.
>> + */
>> + rt->fib6_table = table;
>> +
>> return rt;
>> out:
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