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

[Eric Blake]

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?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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