Re: [PATCH 2/3] mmc: sdhci-acpi: Check device status before calling fix_up_power()

[Hans de Goede]

Hi,

On 03-03-17 10:09, Jean Delvare wrote:
> 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?

Not that bad really, thinking more about this, since drivers/mmc/host/sdhci-acpi.c
is a platform driver, its probe function will never get called if
!device->status.present, since the acpi-subsys then will not
instantiate a platform device for the acpi-dev in question at all.

So a better fix would be to just drop the superfluous
check. I'll send a new version doing this.

Regards,

Hans


> 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@xxxxxxxxxx>
> > ---
> >  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;