Subject: Re: [patch net-next RFC 1/2] fib: introduce fib notification infrastructure

From: Roopa Prabhu <[email-masked]>
Date: Mon, 19 Sep 2016 07:53:07 -0700

On 9/18/16, 11:06 PM, Jiri Pirko wrote:
> Mon, Sep 19, 2016 at 01:23:47AM CEST, [email-masked] wrote:
>> On 9/6/16, 5:01 AM, Jiri Pirko wrote:
>>> From: Jiri Pirko <[email-masked]>
>>>
>>> This allows to pass information about added/deleted fib entries to
>>> whoever is interested. This is done in a very similar way as devinet
>>> notifies address additions/removals.
>>>
>>> Signed-off-by: Jiri Pirko <[email-masked]>
>>> ---

[snip]
>>>  
>>>  #define KEYLENGTH	(8*sizeof(t_key))
>>> @@ -1190,6 +1221,10 @@ int fib_table_insert(struct fib_table *tb, struct fib_config *cfg)
>>>  			fib_release_info(fi_drop);
>>>  			if (state & FA_S_ACCESSED)
>>>  				rt_cache_flush(cfg->fc_nlinfo.nl_net);
>>> +
>>> +			call_fib_notifiers(FIB_EVENT_TYPE_ADD, key, plen, fi,
>>> +					   new_fa->fa_tos, cfg->fc_type,
>>> +					   tb->tb_id, cfg->fc_nlflags);
>>>  			rtmsg_fib(RTM_NEWROUTE, htonl(key), new_fa, plen,
>>>  				tb->tb_id, &cfg->fc_nlinfo, NLM_F_REPLACE);
>>>  
>>> @@ -1241,6 +1276,8 @@ int fib_table_insert(struct fib_table *tb, struct fib_config *cfg)
>>>  		tb->tb_num_default++;
>>>  
>>>  	rt_cache_flush(cfg->fc_nlinfo.nl_net);
>>> +	call_fib_notifiers(FIB_EVENT_TYPE_ADD, key, plen, fi, tos,
>>> +			   cfg->fc_type, tb->tb_id, cfg->fc_nlflags);
>>
>> It appears that this is in addition to the existing switchdev_fib_ipv4_add call right above this.
>> Is the intent to do both ?. i don't see a need to do both.
> I already have patchset improved that it removes the switchdev fib code.
> Have to do some more testing, will send it soon.

ok, ack.
>
>
>> and switchdev_fib_ipv4_add  offloads before the route is added to the kernel.
>> But the notifier seems to fire after the route is added to the kernel.
> Yeah, I wanted to align it with rtmsg_fib calls. Also I think it makes
> sense to have slowpath ready before offload.
>

ok, ..but..that changes existing behavior though. and if the hw route add fails...,
you may have inconsistent state between hw and sw.