linux-kernel - Re: [PATCH 1/2] power: sysfs: Add link to wakeup class device.

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Date:   Fri, 6 Sep 2019 16:40:25 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Ravi Chandra Sadineni <ravisadineni@...omium.org>
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        x86@...nel.org, rjw@...ysocki.net, pavel@....cz,
        len.brown@...el.com, gregkh@...uxfoundation.org, bhe@...hat.com,
        dyoung@...hat.com, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, tbroch@...omium.org, trong@...gle.com
Subject: Re: [PATCH 1/2] power: sysfs: Add link to wakeup class device.

Hi Ravi,

On Wed, Jul 24, 2019 at 10:43:54AM -0700, Ravi Chandra Sadineni wrote:
> https://patchwork.kernel.org/patch/11045069/ creates a virtual
> device

To refer to unsubmitted patches in the commit message it is
probably better to use the subject ("PM / wakeup: show wakeup
sources stats in sysfs") and add a link after '---', or say
"${subject}" [1] and put the link at the bottom of the commit message

You might want to try again now that the patch has landed :)

> under wakeup class for each wake capable device exposing all related
> sysfs attributes. But there isn't a symlink from the actual device
> node to these virtual devices. This patch creates a symlink from the
> actual device to the corresponding wakeup_source device under wakeup
> class.

> Signed-off-by: Ravi Chandra Sadineni <ravisadineni@...omium.org>
> ---
>  drivers/base/power/power.h  |  2 ++
>  drivers/base/power/sysfs.c  | 25 +++++++++++++++++++++++++
>  drivers/base/power/wakeup.c |  2 ++
>  3 files changed, 29 insertions(+)
> 
> diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
> index c511def48b48..32b0f5c080a9 100644
> --- a/drivers/base/power/power.h
> +++ b/drivers/base/power/power.h
> @@ -67,6 +67,8 @@ extern void dpm_sysfs_remove(struct device *dev);
>  extern void rpm_sysfs_remove(struct device *dev);
>  extern int wakeup_sysfs_add(struct device *dev);
>  extern void wakeup_sysfs_remove(struct device *dev);
> +extern void wakeup_source_sysfs_link_add(struct device *dev);
> +extern void wakeup_source_sysfs_link_remove(struct device *dev);

the names seem a bit clunky, how about wakeup_sysfs_add/remove_link()?

>  extern int pm_qos_sysfs_add_resume_latency(struct device *dev);
>  extern void pm_qos_sysfs_remove_resume_latency(struct device *dev);
>  extern int pm_qos_sysfs_add_flags(struct device *dev);
> diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
> index d713738ce796..fbbdb7b16ac5 100644
> --- a/drivers/base/power/sysfs.c
> +++ b/drivers/base/power/sysfs.c
> @@ -95,6 +95,7 @@
>  const char power_group_name[] = "power";
>  EXPORT_SYMBOL_GPL(power_group_name);
>  
> +static const char wakeup_source_symlink_name[] = "wakeup_source";
>  static const char ctrl_auto[] = "auto";
>  static const char ctrl_on[] = "on";
>  
> @@ -679,6 +680,30 @@ int dpm_sysfs_add(struct device *dev)
>  	return rc;
>  }
>  
> +void wakeup_source_sysfs_link_add(struct device *dev)
> +{
> +	struct wakeup_source *ws;
> +	int err;
> +
> +	ws = dev->power.wakeup;
> +	if (ws && ws->dev) {
> +		err = sysfs_add_link_to_group(&dev->kobj, power_group_name,
> +			&ws->dev->kobj, wakeup_source_symlink_name);
> +		if (err) {
> +			dev_err(dev,
> +				"could not add %s symlink err %d\n",

I'd suggest

				"could not add '%s' symlink: %d\n",

or

				"could not add 'wakeup_source' symlink: %d\n",

the latter is easier to grep.

> +				wakeup_source_symlink_name,
> +				err);
> +		}
> +	}
> +}
> +
> +void wakeup_source_sysfs_link_remove(struct device *dev)
> +{
> +	sysfs_remove_link_from_group(&dev->kobj, power_group_name,
> +		wakeup_source_symlink_name);
> +}
> +
>  int wakeup_sysfs_add(struct device *dev)
>  {
>  	return sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
> index fe779fe13a7f..87dfe401b035 100644
> --- a/drivers/base/power/wakeup.c
> +++ b/drivers/base/power/wakeup.c
> @@ -270,6 +270,7 @@ static int device_wakeup_attach(struct device *dev, struct wakeup_source *ws)
>  	if (dev->power.wakeirq)
>  		device_wakeup_attach_irq(dev, dev->power.wakeirq);
>  	spin_unlock_irq(&dev->power.lock);
> +	wakeup_source_sysfs_link_add(dev);
>  	return 0;
>  }
>  
> @@ -391,6 +392,7 @@ static struct wakeup_source *device_wakeup_detach(struct device *dev)
>  	ws = dev->power.wakeup;
>  	dev->power.wakeup = NULL;
>  	spin_unlock_irq(&dev->power.lock);
> +	wakeup_source_sysfs_link_remove(dev);

you want to do this before the wakeup source is detached.