netdev - Re: [patch net-next v2 1/3] team: handle sending port list in the same way option list is sent

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Message-ID: <20130204162806.GA1544@minipsycho.orion>
Date:	Mon, 4 Feb 2013 17:28:06 +0100
From:	Jiri Pirko <jiri@...nulli.us>
To:	Pablo Neira Ayuso <pablo@...filter.org>
Cc:	netdev@...r.kernel.org, davem@...emloft.net, fbl@...hat.com
Subject: Re: [patch net-next v2 1/3] team: handle sending port list in the
 same way option list is sent

Mon, Feb 04, 2013 at 05:03:04PM CET, pablo@...filter.org wrote:
>On Sat, Feb 02, 2013 at 10:04:22AM +0100, Jiri Pirko wrote:
>> Sat, Feb 02, 2013 at 02:29:28AM CET, pablo@...filter.org wrote:
>> >On Sat, Feb 02, 2013 at 12:31:47AM +0100, Jiri Pirko wrote:
>> >> Fri, Feb 01, 2013 at 09:43:10PM CET, pablo@...filter.org wrote:
>> >> >On Fri, Feb 01, 2013 at 08:00:26PM +0100, Jiri Pirko wrote:
>> >> >> >> +send_done:
>> >> >> >> +	nlh = nlmsg_put(skb, portid, seq, NLMSG_DONE, 0, flags | NLM_F_MULTI);
>> >> >> >> +	if (!nlh) {
>> >> >> >> +		err = __send_and_alloc_skb(&skb, team, portid, send_func);
>> >> >> >> +		if (err)
>> >> >> >> +			goto errout;
>> >> >> >> +		goto send_done;
>> >> >> >> +	}
>> >> >> >
>> >> >> >I'd suggest to use netlink_dump_start for this, so you don't need to
>> >> >> >manually create the NLMSG_DONE message.
>> >> >> 
>> >> >> I believe that is not possible for genl
>> >> >
>> >> >By looking at net/netlink/genetlink.c, you can make it by means of the
>> >> >.dumpit callback in struct genl_ops. You have to pass NLM_F_DUMP from
>> >> >user-space to hit that code.
>> >> 
>> >> Correct. But I need to do unsolicited multicast messages as well. And
>> >> that can't be resolved by dumpit.
>> >
>> >Interesting. Why do you need multi-part multicast event messages?
>> 
>> Messages are too big to fit one GENLMSG_DEFAULT_SIZE message.
>
>nfnetlink_log may use bigger messages than 1 memory page to deliver
>multicast events if configured to include the entire packet
>(NFULNL_COPY_PACKET).
>
>I'd suggest to calculate the message size in run-time and allocate
>memory you need according to that, several netfilter subsystem are
>doing so.

I recall I had some issues with longer messages on the userspace part,
I'm not sure what that was exactly. I decided to do this in multipart
messages and in order to do not break userspace I would like to continue
to do so.


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