Re: [Qemu-devel] [PATCH] qapi: InitSocketAddress: add keepalive option

[Markus Armbruster]

Vladimir Sementsov-Ogievskiy <address@hidden> writes:

> 06.06.2019 14:17, Daniel P. Berrangé wrote:
>> On Thu, Jun 06, 2019 at 01:15:33PM +0300, Vladimir Sementsov-Ogievskiy wrote:
>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>>> ---
>>>
>>> Hi all!
>>>
>>> This is a continuation of "[PATCH v2 0/2] nbd: enable keepalive", but
>>> it's a try from another side, so almost nothing common with v2.

Please explain intended use of your new option in your commit message.

>>>   qapi/sockets.json   |  5 ++++-
>>>   util/qemu-sockets.c | 13 +++++++++++++
>>>   2 files changed, 17 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/qapi/sockets.json b/qapi/sockets.json
>>> index fc81d8d5e8..aefa024051 100644
>>> --- a/qapi/sockets.json
>>> +++ b/qapi/sockets.json
>>> @@ -53,6 +53,8 @@
>>>   #
>>>   # @ipv6: whether to accept IPv6 addresses, default try both IPv4 and IPv6
>>>   #
>>> +# @keepalive: enable keepalive when connecting to this socket (Since 4.1)
>>> +#
>>>   # Since: 1.3
>>>   ##
>>>   { 'struct': 'InetSocketAddress',
>>> @@ -61,7 +63,8 @@
>>>       '*numeric':  'bool',
>>>       '*to': 'uint16',
>>>       '*ipv4': 'bool',
>>> -    '*ipv6': 'bool' } }
>>> +    '*ipv6': 'bool',
>>> +    '*keepalive': 'bool' } }

I know the C identifier is SO_KEEPALIVE, but let's stick to proper
English words in QMP: keep-alive.

>>>   
>>>   ##
>>>   # @UnixSocketAddress:
>>> diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
>>> index 8850a280a8..d2cd2a9d4f 100644
>>> --- a/util/qemu-sockets.c
>>> +++ b/util/qemu-sockets.c
>>> @@ -457,6 +457,19 @@ int inet_connect_saddr(InetSocketAddress *saddr, Error 
>>> **errp)
>>>       }
>>>   
>>>       freeaddrinfo(res);
>>> +
>>> +    if (saddr->keepalive) {
>> 
>> IIUC, best practice is to use 'saddr->has_keepalive && saddr->keepalive'
>
> As I remember, now all optional fields are zeroed. But I'm not against 
> stricter condition.

As far as I'm concerned, relying on zero-initialization of optional
members is fine.

>
>> 
>>> +        int val = 1;
>>> +        int ret = qemu_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
>>> +                                  &val, sizeof(val));
>>> +
>>> +        if (ret < 0) {
>>> +            error_setg_errno(errp, errno, "Unable to set KEEPALIVE");
>>> +            close(sock);
>>> +            return -1;
>>> +        }
>>> +    }
>>> +
>>>       return sock;
>>>   }

Possibly ignorant question: why obey the keep-alive option for active
connections (made with inet_connect_saddr()), but not passive ones (made
with inet_listen_saddr() + accept())?

Do you need to update inet_parse()?