linux-kernel - Re: [PATCH 00/11] RFC: KBUS messaging subsystem

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Message-ID: <20110322133640.5d5c88e4@bike.lwn.net>
Date:	Tue, 22 Mar 2011 13:36:40 -0600
From:	Jonathan Corbet <corbet@....net>
To:	Tony Ibbs <tibs@...yibbs.co.uk>,
	Grant Likely <grant.likely@...retlab.ca>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Linux-embedded <linux-embedded@...r.kernel.org>,
	Tibs at Kynesim <tibs@...esim.co.uk>,
	Richard Watts <rrw@...esim.co.uk>
Subject: Re: [PATCH 00/11] RFC: KBUS messaging subsystem

On Fri, 18 Mar 2011 17:21:09 +0000
Tony Ibbs <tibs@...yibbs.co.uk> wrote:

> KBUS is a lightweight, Linux kernel mediated messaging system,
> particularly intended for use in embedded environments.

I've spent a bit of time looking at this code...this isn't a detailed
review by any stretch, more like a few impressions.

- Why kbus over, say, a user-space daemon and unix-domain sockets?  I'm
  not sure I see the advantage that comes with putting this into kernel
  space.

- The interface is ... creative.  If you have to do this in kernel space,
  it would be nice to do away with the split write()/ioctl() API for
  reading or writing messages.  It seems like either a write(), OR an
  ioctl() with a message data pointer would suffice; that would cut the
  number of syscalls the applications need to make too.

  Even better might be to just use the socket API.

- Does anything bound the size of a message fed into the kernel with
  write()?  I couldn't find it.  It seems like an application could
  consume arbitrary amounts of kernel memory.

- It would be good to use the kernel's dynamic debugging and tracing
  facilities rather than rolling your own.

- There's lots of kmalloc()/memset() pairs that could be kzalloc().

That's as far as I could get for now.

Thanks,

jon
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