netdev - Re: [PATCH net-next 07/13] ipv6: Move gateway checks to a fib6

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Date:   Wed, 27 Mar 2019 08:21:43 -0600
From:   David Ahern <dsahern@...il.com>
To:     Ido Schimmel <idosch@...lanox.com>,
        David Ahern <dsahern@...nel.org>
Cc:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Jiri Pirko <jiri@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: Re: [PATCH net-next 07/13] ipv6: Move gateway checks to a fib6_nh
 setting

On 3/27/19 3:08 AM, Ido Schimmel wrote:
> On Tue, Mar 26, 2019 at 08:29:36PM -0700, David Ahern wrote:
>> @@ -989,8 +989,11 @@ static void ip6_rt_copy_init(struct rt6_info *rt, struct fib6_info *ort)
>>  
>>  	rt->rt6i_dst = ort->fib6_dst;
>>  	rt->rt6i_idev = dev ? in6_dev_get(dev) : NULL;
>> -	rt->rt6i_gateway = ort->fib6_nh.nh_gw;
>>  	rt->rt6i_flags = ort->fib6_flags;
>> +	if (ort->fib6_nh.fib_nh_has_gw) {
>> +		rt->rt6i_gateway = ort->fib6_nh.nh_gw;
>> +		rt->rt6i_flags |= RTF_GATEWAY;
> 
> Not sure I understand why this line is needed. Can you explain?

The RTF_GATEWAY flag in an rt6_info still has many users.

> 
>> +	}
>>  	rt6_set_from(rt, ort);
>>  #ifdef CONFIG_IPV6_SUBTREES
>>  	rt->rt6i_src = ort->fib6_src;
>> @@ -1870,7 +1873,7 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
> 
> ...
> 
>> @@ -3134,7 +3138,7 @@ static struct fib6_info *ip6_route_info_create(struct fib6_config *cfg,
>>  	} else
>>  		rt->fib6_prefsrc.plen = 0;
>>  
>> -	rt->fib6_flags = cfg->fc_flags;
>> +	rt->fib6_flags = cfg->fc_flags & ~RTF_GATEWAY;
> 
> This is going to break mlxsw. See:
> 
> mlxsw_sp_fib6_rt_can_mp()
> mlxsw_sp_rt6_is_gateway()

hmmm... not sure how I missed those. Will rescan the code for any other
missed checks on a fib6_info.