Re: [Qemu-devel] [PATCH v3] qapi: Add InetSocketAddress member keep-alive

[Vladimir Sementsov-Ogievskiy]

19.07.2019 23:29, Eric Blake wrote:
> On 6/25/19 8:32 AM, Markus Armbruster wrote:
>> I apologize for dragging my feet on this review.
>>
>> Vladimir Sementsov-Ogievskiy <address@hidden> writes:
>>
>>> It's needed to provide keepalive for nbd client to track server
>>> availability.
>>>
>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>>> ---
>>>
> 
>>> +++ b/qapi/sockets.json
>>> @@ -53,6 +53,9 @@
>>>   #
>>>   # @ipv6: whether to accept IPv6 addresses, default try both IPv4 and IPv6
>>>   #
>>> +# @keep-alive: enable keep-alive when connecting to this socket. Not 
>>> supported
>>> +#              for server-side connections. (Since 4.1)
> 
> It looks like this missed 4.1.  Are you planning on sending v4, to address
> 
>>> +#
>>
>> Is "server-side connection" is an established term?
>>
>> For what it's worth, "passive socket" is, see listen(2).
>>
>>>   # Since: 1.3
>>>   ##
>>>   { 'struct': 'InetSocketAddress',
>>> @@ -61,7 +64,8 @@
>>>       '*numeric':  'bool',
>>>       '*to': 'uint16',
>>>       '*ipv4': 'bool',
>>> -    '*ipv6': 'bool' } }
>>> +    '*ipv6': 'bool',
>>> +    '*keep-alive': 'bool' } }
>>>   
>>>   ##
>>>   # @UnixSocketAddress:
>>> diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
>>> index 8850a280a8..813063761b 100644
>>> --- a/util/qemu-sockets.c
>>> +++ b/util/qemu-sockets.c
>>> @@ -438,6 +438,12 @@ int inet_connect_saddr(InetSocketAddress *saddr, Error 
>>> **errp)
>>>       struct addrinfo *res, *e;
>>>       int sock = -1;
>>>   
>>> +    if (saddr->keep_alive) {
>>> +        error_setg(errp, "keep-alive options is not supported for 
>>> server-side "
>>> +                   "connection");
>>> +        return -1;
>>> +    }
>>> +
>>>       res = inet_parse_connect_saddr(saddr, errp);
>>>       if (!res) {
>>>           return -1;
>>
>> I'm afraid you added this to the wrong function; ...
>>
>>> @@ -457,6 +463,19 @@ int inet_connect_saddr(InetSocketAddress *saddr, Error 
>>> **errp)
>>>       }
>>>   
>>>       freeaddrinfo(res);
>>> +
>>> +    if (saddr->keep_alive) {
>>
>> ... it renders this code unreachable.
>>
>> I guess the "not supported for passive sockets" check should go into
>> inet_listen_saddr() instead.
> 
> this comment?
> 

Sorry for big delay, will resend for 4.2 soon.

-- 
Best regards,
Vladimir