Subject: Re: [1/1] connector/CBUS: new messaging subsystem. Revision number next.

From: Evgeniy Polyakov <[email-masked]>
Date: Wed, 27 Apr 2005 09:32:06 +0400

On Wed, 2005-04-27 at 00:16 -0500, Dmitry Torokhov wrote:
> On Tuesday 26 April 2005 23:06, Evgeniy Polyakov wrote:
> > Let's clarify that we are talking about userspace->kernelspace
> > direction.
> > Only for that messages callback path is invoked.
> 
> What about kernelspace->userspace or kernelspace->kernelspace?
> From what I see nothing stops kernel code from calling cn_netlink_send,
> in fact your cbus does exactly that. So I am confused why you singled
> out userspace->kernelspace direction.

You miunderstand the code -
cn_netlink_send() never ends up in callback invocation, 
it can only deliver messages in kernelspace->userspace direction.
kernelspace->userspace direction ends up adding buffer into
socket queue, from which userspace may read data using recv() system
call.
There is no kernelspace->kernelspace sending possibility 
except by creating new socket in userspace and sendmsg/recvmsg 
interception/using, but that is the same as reading from userspace.

-- 
        Evgeniy Polyakov

Crash is better than data corruption -- Arthur Grabowski