linux-kernel - Re: [PATCH] powerpc/fsl_rio: fix a improper release in fsl_rio

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Message-Id: <20251220134230.712676-1-lihaoxiang@isrc.iscas.ac.cn>
Date: Sat, 20 Dec 2025 21:42:30 +0800
From: Haoxiang Li <lihaoxiang@...c.iscas.ac.cn>
To: chleroy@...nel.org
Cc: alex.bou9@...il.com,
	lihaoxiang@...c.iscas.ac.cn,
	linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	maddy@...ux.ibm.com,
	mpe@...erman.id.au,
	mporter@...nel.crashing.org,
	npiggin@...il.com
Subject: Re: [PATCH] powerpc/fsl_rio: fix a improper release in fsl_rio_setup()

On Sat, 20 Dec 2025 11:45:10 +0100, Christophe Leroy wrote:
> Your explanation is unclear. It is correct that put_device() is the 
> correct way to drop the device reference, and it is already what 
> rio_register_mport() does. Why do you need to move it out of 
> rio_register_mport() ? This is what you have to explain.

Sorry for the unclear changelog. I think if device_register() in
rio_register_mport() fails, put_device() is already called. Then,
the error path in fsl_rio_setup() also kfree() the port. I suspected
a potential double-free issue here, although I am unsure whether this interpretation is correct.

> AI code review or human code review ?

Human review.

> Why do you remove this kfree() ? By doing this you will leak the port 
> pointer allocated earlier in the loop by kzalloc()

I just thought after device_register(), the cleanup should be done by
put_device().

I would appreciate your clarification.

Thanks,
Haoxiang Li