Re: [PATCH v3 10/16] ipmi: kcs_bmc: Don't enforce single-open policy in the kernel

Andrew Jeffery andrew at
Mon May 24 10:39:22 AEST 2021

On Sat, 22 May 2021, at 03:00, Corey Minyard wrote:
> On Mon, May 10, 2021 at 03:12:07PM +0930, Andrew Jeffery wrote:
> > Soon it will be possible for one KCS device to have multiple associated
> > chardevs exposed to userspace (for IPMI and raw-style access). However,
> > don't prevent userspace from:
> > 
> > 1. Opening more than one chardev at a time, or
> > 2. Opening the same chardev more than once.
> > 
> > System behaviour is undefined for both classes of multiple access, so
> > userspace must manage itself accordingly.
> I don't understand why you want to allow this.  If the second open won't
> work right, then why allow it?  Why remove code that causes the second
> open to error?

Really I was just shifting the problem to userspace so it wasn't 
something I needed to address in the kernel. It seems I'm alone in 
thinking this is a good idea, as yourself, Zev, William and Joel 
(privately) have pushed back against it. Initially the idea was tied up 
in how I was doing some interrupt handling, but in revising the code 
that problem has gone away.

I'll just drop this patch and save everyone the heartburn of arguing 
about it :)


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