linux-kernel - Re: [PATCH v2 1/1] mfd: intel-lpss: Fix too early PM enablement in the ACPI ->probe()

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Date:   Tue, 2 Nov 2021 05:42:35 +0000
From:   Aditya Garg <gargaditya08@...e.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     Lee Jones <lee.jones@...aro.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Orlando Chamberlain <redecorating@...tonmail.com>
Subject: Re: [PATCH v2 1/1] mfd: intel-lpss: Fix too early PM enablement in
 the ACPI ->probe()



> On 02-Nov-2021, at 12:30 AM, Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> 
> The runtime PM callback may be called as soon as the runtime PM facility
> is enabled and activated. It means that ->suspend() may be called before
> we finish probing the device in the ACPI case. Hence, NULL pointer
> dereference:
> 
>  intel-lpss INT34BA:00: IRQ index 0 not found
>  BUG: kernel NULL pointer dereference, address: 0000000000000030
>  ...
>  Workqueue: pm pm_runtime_work
>  RIP: 0010:intel_lpss_suspend+0xb/0x40 [intel_lpss]
> 
> To fix this, first try to register the device and only after that enable
> runtime PM facility.
> 
> Fixes: 4b45efe85263 ("mfd: Add support for Intel Sunrisepoint LPSS devices")
> Reported-by: Orlando Chamberlain <redecorating@...tonmail.com>
> Reported-by: Aditya Garg <gargaditya08@...e.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Tested-by: Aditya Garg <gargaditya08@...e.com>
> ---
> v2: added tag (Aditya), returned 0 explicitly at the end of ->probe()
It works
> drivers/mfd/intel-lpss-acpi.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/intel-lpss-acpi.c b/drivers/mfd/intel-lpss-acpi.c
> index 3f1d976eb67c..f2ea6540a01e 100644
> --- a/drivers/mfd/intel-lpss-acpi.c
> +++ b/drivers/mfd/intel-lpss-acpi.c
> @@ -136,6 +136,7 @@ static int intel_lpss_acpi_probe(struct platform_device *pdev)
> {
> 	struct intel_lpss_platform_info *info;
> 	const struct acpi_device_id *id;
> +	int ret;
> 
> 	id = acpi_match_device(intel_lpss_acpi_ids, &pdev->dev);
> 	if (!id)
> @@ -149,10 +150,14 @@ static int intel_lpss_acpi_probe(struct platform_device *pdev)
> 	info->mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> 	info->irq = platform_get_irq(pdev, 0);
> 
> +	ret = intel_lpss_probe(&pdev->dev, info);
> +	if (ret)
> +		return ret;
> +
> 	pm_runtime_set_active(&pdev->dev);
> 	pm_runtime_enable(&pdev->dev);
> 
> -	return intel_lpss_probe(&pdev->dev, info);
> +	return 0;
> }
> 
> static int intel_lpss_acpi_remove(struct platform_device *pdev)
> -- 
> 2.33.0
>