netdev - Re: [PATCH v2 net-next 4/7] ipv6: Plumb support for nexthop object in a fib6

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Date:   Tue, 4 Jun 2019 14:17:28 -0600
From:   David Ahern <dsahern@...il.com>
To:     Martin Lau <kafai@...com>
Cc:     Wei Wang <weiwan@...gle.com>, David Ahern <dsahern@...nel.org>,
        "David S . Miller" <davem@...emloft.net>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        "idosch@...lanox.com" <idosch@...lanox.com>,
        "saeedm@...lanox.com" <saeedm@...lanox.com>
Subject: Re: [PATCH v2 net-next 4/7] ipv6: Plumb support for nexthop object in
 a fib6_info

On 6/3/19 11:29 PM, Martin Lau wrote:
> On Mon, Jun 03, 2019 at 07:36:06PM -0600, David Ahern wrote:
>> On 6/3/19 6:58 PM, Martin Lau wrote:
>>> I have concern on calling ip6_create_rt_rcu() in general which seems
>>> to trace back to this commit
>>> dec9b0e295f6 ("net/ipv6: Add rt6_info create function for ip6_pol_route_lookup")
>>>
>>> This rt is not tracked in pcpu_rt, rt6_uncached_list or exception bucket.
>>> In particular, how to react to NETDEV_UNREGISTER/DOWN like
>>> the rt6_uncached_list_flush_dev() does and calls dev_put()?
>>>
>>> The existing callers seem to do dst_release() immediately without
>>> caching it, but still concerning.
>>
>> those are the callers that don't care about the dst_entry, but are
>> forced to deal with it. Removing the tie between fib lookups an
>> dst_entry is again the right solution.
> Great to know that there will be a solution.  It would be great
> if there is patch (or repo) to show how that may look like on
> those rt6_lookup() callers.

Not 'will be', 'there is' a solution now. Someone just needs to do the
conversions and devise the tests for the impacted users.