[Ocfs2-devel] [patch 03/11] ocfs2/o2net: incorrect to terminate accepting connections loop upon rejecting an invalid one

[Srinivas Eeda]

On 01/24/2014 01:55 PM, Mark Fasheh wrote:
> On Fri, Jan 24, 2014 at 12:47:02PM -0800, akpm at linux-foundation.org wrote:
>> From: Tariq Saeed <tariq.x.saeed at oracle.com>
>> Subject: ocfs2/o2net: incorrect to terminate accepting connections loop upon rejecting an invalid one
>>
>> When o2net-accept-one() rejects an illegal connection, it terminates the
>> loop picking up the remaining queued connections.  This fix will continue
>> accepting connections till the queue is emtpy.
>>
>> Addresses Orabug 17489469.
> Thanks for sending this, review comments below.
>
>
>> diff -puN fs/ocfs2/cluster/tcp.c~ocfs2-o2net-incorrect-to-terminate-accepting-connections-loop-upon-rejecting-an-invalid-one fs/ocfs2/cluster/tcp.c
>> --- a/fs/ocfs2/cluster/tcp.c~ocfs2-o2net-incorrect-to-terminate-accepting-connections-loop-upon-rejecting-an-invalid-one
>> +++ a/fs/ocfs2/cluster/tcp.c
>> @@ -1826,7 +1826,7 @@ int o2net_register_hb_callbacks(void)
>>   
>>   /* ------------------------------------------------------------ */
>>   
>> -static int o2net_accept_one(struct socket *sock)
>> +static int o2net_accept_one(struct socket *sock, int *more)
>>   {
>>   	int ret, slen;
>>   	struct sockaddr_in sin;
>> @@ -1837,6 +1837,7 @@ static int o2net_accept_one(struct socke
>>   	struct o2net_node *nn;
>>   
>>   	BUG_ON(sock == NULL);
>> +	*more = 0;
>>   	ret = sock_create_lite(sock->sk->sk_family, sock->sk->sk_type,
>>   			       sock->sk->sk_protocol, &new_sock);
>>   	if (ret)
>> @@ -1848,6 +1849,7 @@ static int o2net_accept_one(struct socke
>>   	if (ret < 0)
>>   		goto out;
>>   
>> +	*more = 1;
>>   	new_sock->sk->sk_allocation = GFP_ATOMIC;
>>   
>>   	ret = o2net_set_nodelay(new_sock);
>> @@ -1949,8 +1951,15 @@ out:
>>   static void o2net_accept_many(struct work_struct *work)
>>   {
>>   	struct socket *sock = o2net_listen_sock;
>> -	while (o2net_accept_one(sock) == 0)
>> +	int	more;
>> +	int	err;
>> +
>> +	for (;;) {
>> +		err = o2net_accept_one(sock, &more);
>> +		if (!more)
>> +			break;
> We're throwing out 'err' here and trusting the variable 'more'. However, err
> could be set and more would be 0 regardless of whether there actually are
> more connections to be had. This makes more sense given when 'more' is set:
Hi Mark,

thanks for reviewing this :). Please correct me if I am wrong.

The idea was if "accept" itself fails exit the loop, otherwise continue 
scanning all queued connections. For eg: if a connection request from 
unknown node followed by known node happens at the same time, we can 
ignore the ret value of the first connection request and still continue 
accepting the next connection.

ret value appears to be of not much importance other than just for 
logging or debugging purpose.


>
> 	if (err)
> 		break;
> 	/* only trust the value of 'more' when err == 0 */
> 	if (more)
> 		break;
>
> Thanks,
> 	--Mark
>
> --
> Mark Fasheh
>
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