Subject: Re: [PATCH 3/3] sock-diag: Report shutdown for inet and unix sockets

From: Pavel Emelyanov <[email-masked]>
Date: Tue, 23 Oct 2012 21:53:02 +0400

On 10/23/2012 09:42 PM, David Miller wrote:
> From: Pavel Emelyanov <[email-masked]>
> Date: Tue, 23 Oct 2012 20:28:22 +0400
> 
>> +static inline int shutdown_mask2u(int mask)
>> +{
>> +	/*
>> +	 * map
>> +	 * 	RCV_SHUTDOWN -> SHUT_RD
>> +	 * 	SEND_SHUTDOWN -> SHUT_WR
>> +	 * 	SHUTDOWN_MASK -> SHUT_RDWR
>> +	 */
>> +
>> +	return mask - 1;
>> +}
> 
> This is horrible.
> 
> You're returning "-1" when the socket hasn't been shutdown in any way.
> 
> Do this:
> 
> 1) Use a '1' based encoding like the kernel codes so that '0' means
>    no shutdown, as any sane interface would.  That's why we use that
>    representation internally.
> 
> 2) Get rid of all of this extension crap, and just report this value
>    in the pad byte.  In older kernels it will just be zero, which is
>    fine.

The response message of inet-diag never had any pad bytes, I'll have to
add the new attrtype (the unix-diag response has one, but I plan to add
attrtype there too for uniformity).

Thanks,
Pavel