From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] net: netlink: don't try unicast when dst_pid is zero
 for NETLINK_USERSOCK
Date: Fri, 13 May 2011 16:48:16 -0400 (EDT)
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From: Changli Gao <xiaosuo@gmail.com>
Date: Fri, 13 May 2011 14:24:54 +0800

> For NETLINK_USERSOCK, no one listens on PID 0, so sending a message only to
> to a multicast group should not return -ECONNREFUSED.
> 
> Signed-off-by: Changli Gao <xiaosuo@gmail.com>

I don't think this is a great idea, creating different semantics for
NETLINK_USERSOCK vs. other types.

You have to set the pid to something which will receive the unicast
message, and then you can also (on top of that) send it to a multicast
group as well.

But the base operation is always the unicast send, and that is what
determines success/failure of the operation.

I'm not applying this patch.