linux-kernel - Re: [PATCH 2/3] mmc: sdhci-acpi: Check device status before calling fix_up

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Date:   Fri, 3 Mar 2017 10:09:05 +0100
From:   Jean Delvare <jdelvare@...e.de>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Jean Delvare <jdelvare@...e.com>, Takashi Iwai <tiwai@...e.de>,
        russianneuromancer@...ru, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] mmc: sdhci-acpi: Check device status before calling
 fix_up_power()

Hi Hans, Adrian,

On Sat, 25 Feb 2017 18:23:56 +0100, Hans de Goede wrote:
> Calling acpi_device_fix_up_power() on a device which is not present
> is not a good idea.

How bad is it?

This was introduced by commit e5bbf30733f9, which was backported to
several stable branches. If it causes real trouble then this fix-up
patch should be annotated with

Fixes: e5bbf30733f9 ("mmc: sdhci-acpi: Ensure connected devices are powered when")

and Cc's to stable@, so it can be propagated to all affected trees.

> While at it also call acpi_bus_get_status() on the children before
> the status check to make sure that child->status contains valid data.
> 
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> ---
>  drivers/mmc/host/sdhci-acpi.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
> index 96465ff..873beae 100644
> --- a/drivers/mmc/host/sdhci-acpi.c
> +++ b/drivers/mmc/host/sdhci-acpi.c
> @@ -394,15 +394,15 @@ static int sdhci_acpi_probe(struct platform_device *pdev)
>  	if (acpi_bus_get_device(handle, &device))
>  		return -ENODEV;
>  
> +	if (acpi_bus_get_status(device) || !device->status.present)
> +		return -ENODEV;
> +
>  	/* Power on the SDHCI controller and its children */
>  	acpi_device_fix_up_power(device);
>  	list_for_each_entry(child, &device->children, node)
>  		if (child->status.present && child->status.enabled)
>  			acpi_device_fix_up_power(child);
>  
> -	if (acpi_bus_get_status(device) || !device->status.present)
> -		return -ENODEV;
> -
>  	if (sdhci_acpi_byt_defer(dev))
>  		return -EPROBE_DEFER;
>  


-- 
Jean Delvare
SUSE L3 Support