netdev - Re: [PATCH net-next 4/6] inet: frags: use rhashtables for reassembly units

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Date:   Fri, 30 Mar 2018 06:30:42 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>, Florian Westphal <fw@...len.de>,
        Thomas Graf <tgraf@...g.ch>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Alexander Aring <alex.aring@...il.com>,
        Stefan Schmidt <stefan@....samsung.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Nikolay Aleksandrov <nikolay@...hat.com>
Subject: Re: [PATCH net-next 4/6] inet: frags: use rhashtables for reassembly
 units



On 03/30/2018 12:18 AM, Herbert Xu wrote:

> Instead of using the walk interface, how about
> rhashtable_free_and_destroy?

Oh, I was not aware of this beast ;)

I guess I will need to add a cond_resched() in it, right ?

My rough guess is that freeing 30 million frags would take few seconds ;)

> 
>>  void inet_frag_kill(struct inet_frag_queue *fq)
>>  {
>>  	if (del_timer(&fq->timer))
>>  		refcount_dec(&fq->refcnt);
>>  
>>  	if (!(fq->flags & INET_FRAG_COMPLETE)) {
>> -		fq_unlink(fq);
>> +		struct netns_frags *nf = fq->net;
>> +
>> +		fq->flags |= INET_FRAG_COMPLETE;
>> +		rhashtable_remove_fast(&nf->rhashtable, &fq->node, nf->f->rhash_params);
>>  		refcount_dec(&fq->refcnt);
>>  	}
>>  }
> 
> This means that the hash won't inline properly.  Don't know big
> of an issue it is to you.  But you could fix it by doing the same
> hack as rhashtable by making inet_frag_kill an inline function and
> take the rhash_params as an explicit argument.

I will investigate this, thanks !