netdev - Re: [PATCH net] tcp: handle inet_csk_reqsk_queue

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Date:   Fri, 8 Mar 2019 14:34:07 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Guillaume Nault <gnault@...hat.com>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net] tcp: handle inet_csk_reqsk_queue_add() failures



On 03/08/2019 02:22 PM, Guillaume Nault wrote:
> On Fri, Mar 08, 2019 at 01:33:02PM -0800, Eric Dumazet wrote:
>>
>>
>> On 03/08/2019 01:09 PM, Guillaume Nault wrote:
>>> @@ -216,7 +216,12 @@ struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
>>>  		refcount_set(&req->rsk_refcnt, 1);
>>>  		tcp_sk(child)->tsoffset = tsoff;
>>>  		sock_rps_save_rxhash(child, skb);
>>> -		inet_csk_reqsk_queue_add(sk, req, child);
>>> +		if (!inet_csk_reqsk_queue_add(sk, req, child)) {
>>> +			bh_unlock_sock(child);
>>> +			sock_put(child);
>>> +			child = NULL;
>>> +			reqsk_put(req);
>>
>> Since we use reqsk_free(req) in the same function, we can use reqsk_free(req)
>> here as well ?
>>
> That was my first approach, but reqsk_free() doesn't like it:
> 
> static inline void reqsk_free(struct request_sock *req)
> {
>         /* temporary debugging */
> 	WARN_ON_ONCE(refcount_read(&req->rsk_refcnt) != 0);
> ...
> }

Oh right, there is this refcount_set(&req->rsk_refcnt, 1) before the call
to inet_csk_reqsk_queue_add(sk, req, child);

So just change the TFO case only :)