linux-kernel - Re: [PATCH] ipmi: ipmb: initialise event handler read bytes

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Message-ID: <a4cf18d7842c27ea2b570962775d982c0dbc54f0.camel@codeconstruct.com.au>
Date: Wed, 14 Jan 2026 10:10:34 +0800
From: Matt Johnston <matt@...econstruct.com.au>
To: corey@...yard.net
Cc: Andrew Manley <andrew.manley@...lingtech.com>, Corey Minyard
	 <minyard@....org>, openipmi-developer@...ts.sourceforge.net, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ipmi: ipmb: initialise event handler read bytes

Hi Corey,

On Tue, 2026-01-13 at 10:00 -0600, Corey Minyard wrote:
> On Tue, Jan 13, 2026 at 05:41:34PM +0800, Matt Johnston wrote:
> > IPMB doesn't use i2c reads, but the handler needs to set a value.
> > Otherwise an i2c read will return an uninitialised value from the bus
> > driver.
> 
> This is fine, I suppose.  It's probably better to do this.
> 
> Are you actually using this code?  How was it found?

I'm not using IPMB, so haven't tested the patch on hardware.
We received a patch for mctp-i2c read handling, that made me notice 
the uninitialised value problem there. I had a look over other 
i2c_slave_register() kernel users to see if the problem was common
(mctp-i2c used ipmi-ipmb as a bit of a reference during development too).

https://lore.kernel.org/netdev/20260108101829.1140448-1-
zhangjian.3032@...edance.com/
https://lore.kernel.org/netdev/20260113-mctp-read-fix-v1-1-
70c4b59c741c@...econstruct.com.au/

Cheers,
Matt