On Thu, Mar 12, 2020 at 02:32:44PM +0100, Wolfram Sang wrote:
> From: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
>
> i2c_verify_client() can fail, so we need to put the device when that
> happens.
I hope it's not a CoVID-19 makes me mistakenly commented in the first place. :-)
So, theoretically below is possible, but practically it's doubtful.
The I2CSerialBusV2() ACPI resource can be present solely in I²C slave device
nodes according to the specification. However, we might have two possible cases
a) screwed up ACPI table;
b) I²C master which in turn is I²C slave.
While a) has been so far unseen, b) case sounds like plasible for I²C muxes IIUC.
So, I agree with the patch, and sorry for the first reaction.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Fixes: 525e6fabeae2 ("i2c / ACPI: add support for ACPI reconfigure notifications")
> Reported-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
> ---
>
> RFC because I don't know if it can be that the returned dev is not an
> i2c_client. Yet, since it can happen theoretically, I think we should
> have the checks.
>
> drivers/i2c/i2c-core-acpi.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
> index 8f3dbc97a057..8b0ff780919b 100644
> --- a/drivers/i2c/i2c-core-acpi.c
> +++ b/drivers/i2c/i2c-core-acpi.c
> @@ -394,9 +394,17 @@ EXPORT_SYMBOL_GPL(i2c_acpi_find_adapter_by_handle);
> static struct i2c_client *i2c_acpi_find_client_by_adev(struct acpi_device *adev)
> {
> struct device *dev;
> + struct i2c_client *client;
>
> dev = bus_find_device_by_acpi_dev(&i2c_bus_type, adev);
> - return dev ? i2c_verify_client(dev) : NULL;
> + if (!dev)
> + return NULL;
> +
> + client = i2c_verify_client(dev);
> + if (!client)
> + put_device(dev);
> +
> + return client;
> }
>
> static int i2c_acpi_notify(struct notifier_block *nb, unsigned long value,
> --
> 2.20.1
>
--
With Best Regards,
Andy Shevchenko
