Re: [PATCH] PM / devfreq: Add new name attribute for sysfs

Bartlomiej Zolnierkiewicz
2018-08-29T12:50:53Z

Hi Chanwoo,

On Wednesday, August 29, 2018 04:34:06 PM Chanwoo Choi wrote:
> commit 4585fbcb5331 ("PM / devfreq: Modify the device name as devfreq(X) for
> sysfs") changed the node name to devfreq(x). After this commit, it is not
> possible to get the device name through /sys/class/devfreq/devfreq(X)/*.
>
> Add new name attribute in order to get device name.

Could you please describe the issue encountered in more detail
(what the old device name is needed for)?

> Cc: stable@vger.kernel.org
> Fixes: 4585fbcb5331 ("PM / devfreq: Modify the device name as devfreq(X) for sysfs")
> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
> ---
> drivers/devfreq/devfreq.c | 11 +++++++++++
> include/linux/devfreq.h | 3 +++
> 2 files changed, 14 insertions(+)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 4c49bb1330b5..2145563d5ee5 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -620,6 +620,9 @@ struct devfreq *devfreq_add_device(struct device *dev,
> }
> devfreq->max_freq = devfreq->scaling_max_freq;
>
> + devfreq->name = dev_name(devfreq->dev.parent);

It seems that 'dev' can be used instead of 'devfreq->dev.parent'.

> + if (IS_ERR_OR_NULL(devfreq->name))

Error values are not encoded into pointer returned by dev_name()
(drivers/base/ code is only checking for pointer being NULL).

> + return -EINVAL;

This leaks 'devfreq' object and doesn't encode return value into
pointer returned by devfreq_add_device(), it should be replaced by:

err = -EINVAL;
goto err_dev;

> dev_set_name(&devfreq->dev, "devfreq%d",
> atomic_inc_return(&devfreq_no));
> err = device_register(&devfreq->dev);

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland