linux-kernel - RE: [PATCH 3/3] misc: microchip: pci1xxxx: Fix the error handling paths of gp_aux_bus

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Date:   Mon, 19 Sep 2022 17:47:32 +0000
From:   <Kumaravel.Thiagarajan@...rochip.com>
To:     <christophe.jaillet@...adoo.fr>, <arnd@...db.de>,
        <gregkh@...uxfoundation.org>
CC:     <linux-kernel@...r.kernel.org>, <kernel-janitors@...r.kernel.org>,
        <linux-gpio@...r.kernel.org>
Subject: RE: [PATCH 3/3] misc: microchip: pci1xxxx: Fix the error handling
 paths of gp_aux_bus_probe()

> -----Original Message-----
> From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> Sent: Sunday, September 18, 2022 11:58 AM
> To: Kumaravel Thiagarajan - I21417
> <Kumaravel.Thiagarajan@...rochip.com>; Arnd Bergmann
> <arnd@...db.de>; Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: linux-kernel@...r.kernel.org; kernel-janitors@...r.kernel.org;
> Christophe JAILLET <christophe.jaillet@...adoo.fr>; linux-
> gpio@...r.kernel.org
> Subject: [PATCH 3/3] misc: microchip: pci1xxxx: Fix the error handling paths
> of gp_aux_bus_probe()
> 
> There are several issues related to the error handling paths of
> gp_aux_bus_probe():
>    - some resources may be released twice. Once explicitly in the error
>      handling path, and once via the release() function
>    - auxiliary_device_delete() should be called after the first successful
>      auxiliary_device_add()
Thanks for your patch. I had noticed this after one of the reviewers had only partially fixed them
up. I need some time to review and test your patch with the hardware before approving them.

> 
> To fix them, reorder the code:
>    - move the place where we get the irq for the 2nd wrapper.
>    - call kfree() and ida_free() after error checks, rather then in the
>      error handling path.
>    - have the error handling path look like the remove function
> 
> Fixes: 393fc2f5948f ("misc: microchip: pci1xxxx: load auxiliary bus driver for
> the PIO function in the multi-function endpoint of pci1xxxx device.")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> This patch is speculative and untested, review with care.
> 
> Other solutions are possible.
> For example, we could use devm_kzalloc() to simplify the error handling path
> and the release function.
I thought about this but had some doubts whether it will work with the auxiliary bus
architecture as the memory allocated will get tagged with the same device pointer.
I need to do some experiments before taking up this path.

Thank You.

Regards,
Kumar