linux-kernel - Re: [PATCH v1 RESEND] spmi: hisi-spmi-controller: Fix kernel panic on rmmod

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Message-ID: <ZbNq9q5mM6kRq7c3@hovoldconsulting.com>
Date: Fri, 26 Jan 2024 09:19:02 +0100
From: Johan Hovold <johan@...nel.org>
To: Vamshi Gajjela <vamshigajjela@...gle.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
	Stephen Boyd <sboyd@...nel.org>,
	Johan Hovold <johan+linaro@...nel.org>,
	Caleb Connolly <caleb.connolly@...aro.org>,
	linux-kernel@...r.kernel.org, manugautam@...gle.com
Subject: Re: [PATCH v1 RESEND] spmi: hisi-spmi-controller: Fix kernel panic
 on rmmod

On Fri, Jan 26, 2024 at 11:41:53AM +0530, Vamshi Gajjela wrote:
> Ensure consistency in spmi_controller pointers between
> spmi_controller_remove/put and driver spmi_del_controller functions.
> The former requires a pointer to struct spmi_controller, while the
> latter passes a pointer of struct spmi_controller_dev, leading to a
> "Null pointer exception".
> 
> 'nr' member of struct spmi_controller, which serves as an identifier
> for the controller/bus. This value is assigned a dynamic ID in
> spmi_controller_alloc, and overriding it from the driver results in an
> ida_free error "ida_free called for id=xx which is not allocated".

No Fixes tag?

> Signed-off-by: Vamshi Gajjela <vamshigajjela@...gle.com>
> ---
>  drivers/spmi/hisi-spmi-controller.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spmi/hisi-spmi-controller.c b/drivers/spmi/hisi-spmi-controller.c
> index 9cbd473487cb..af51ffe24072 100644
> --- a/drivers/spmi/hisi-spmi-controller.c
> +++ b/drivers/spmi/hisi-spmi-controller.c
> @@ -303,7 +303,6 @@ static int spmi_controller_probe(struct platform_device *pdev)
>  
>  	spin_lock_init(&spmi_controller->lock);
>  
> -	ctrl->nr = spmi_controller->channel;
>  	ctrl->dev.parent = pdev->dev.parent;
>  	ctrl->dev.of_node = of_node_get(pdev->dev.of_node);
>  
> @@ -326,7 +325,8 @@ static int spmi_controller_probe(struct platform_device *pdev)
>  
>  static void spmi_del_controller(struct platform_device *pdev)

This function does not exist in mainline so presumably this is some bug
you've introduced in your downstream driver that you're trying to fix.

So this patch looks all bogus.

>  {
> -	struct spmi_controller *ctrl = platform_get_drvdata(pdev);
> +	struct spmi_controller_dev *spmi_controller = platform_get_drvdata(pdev);
> +	struct spmi_controller *ctrl = spmi_controller->controller;
>  
>  	spmi_controller_remove(ctrl);
>  	spmi_controller_put(ctrl);

Johan