On 3/19/19 9:19 AM, Paolo Abeni wrote:
> Hi,
>
> On Mon, 2019-03-18 at 14:30 -0700, Wei Wang wrote:
>> On Mon, Mar 18, 2019 at 12:48 PM David Ahern <d...@cumulusnetworks.com>
>> wrote:
>>> On 3/18/19 12:36 PM, Xin Long wrote:
>>>> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
>>>> index 4ef4bbd..754777d 100644
>>>> --- a/net/ipv6/route.c
>>>> +++ b/net/ipv6/route.c
>>>> @@ -1040,13 +1040,17 @@ static struct rt6_info *ip6_create_rt_rcu(struct
>>>> fib6_info *rt)
>>>> struct rt6_info *nrt;
>>>>
>>>> if (!fib6_info_hold_safe(rt))
>>>> - return NULL;
>>>> + goto fallback;
>>>>
>>>> nrt = ip6_dst_alloc(dev_net(dev), dev, flags);
>>>> - if (nrt)
>>>> + if (nrt) {
>>>> ip6_rt_copy_init(nrt, rt);
>>>> - else
>>>> + } else {
>>>> fib6_info_release(rt);
>>>> +fallback:
>>>> + nrt = dev_net(dev)->ipv6.ip6_null_entry;
>>>> + dst_hold(&nrt->dst);
>>>> + }
>>>>
>>>> return nrt;
>>>> }
>>>
>>> It seems appropriate for ip6_create_rt_rcu to always return an rt6_info
>>> given its use and v6 design. Since ip6_dst_alloc can also fail
>>> (e.g.,
>>> exceed gc_thresh) the fallback case should apply to both.
>>
>> Agree. We should take care of ip6_dst_alloc() as well.
>
> AFAICS, if ip6_dst_alloc() fails/returns a NULL ptr, with this patch we
> do enter the fallback path (and return a valid rt6_info). I think your
> concerns are already addressed, what I'm missing ?!?
>
you are correct. It should be made clearer from a readability perspective.
