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SubjectRe: [PATCH] power:sysfs: Expose device wakeup_event_count.
On Mon, Jul 22, 2019 at 11:02:58AM -0700, Ravi Chandra Sadineni wrote:
> Device level event_count can help user level daemon to track if a
> praticular device has seen an wake interrupt during a suspend resume
> cycle. Thus expose it via sysfs.
>
> Signed-off-by: Ravi Chandra Sadineni <ravisadineni@chromium.org>
> ---
> Documentation/ABI/testing/sysfs-devices-power | 11 ++++++++++
> drivers/base/power/sysfs.c | 20 +++++++++++++++++++
> 2 files changed, 31 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power
> index 1ca04b4f0489..344549f4013f 100644
> --- a/Documentation/ABI/testing/sysfs-devices-power
> +++ b/Documentation/ABI/testing/sysfs-devices-power
> @@ -89,6 +89,17 @@ Description:
> attribute is not present. If the device is not enabled to wake
> up the system from sleep states, this attribute is empty.
>
> +What: /sys/devices/.../power/wakeup_event_count
> +Date: July 2019
> +Contact: Ravi Chandra sadineni <ravisadineni@chromium.org>
> +Description:
> + The /sys/devices/.../wakeup_event_count attribute contains the
> + number of signaled wakeup events associated with the device.
> + This attribute is read-only. If the device is not capable to
> + wake up the system from sleep states, this attribute is not
> + present. If the device is not enabled to wake up the system
> + from sleep states, this attribute is empty.

The attribute is not "empty" it returns just an empty line.

Is that really a good thing if you are expecting a number?

> +
> What: /sys/devices/.../power/wakeup_active_count
> Date: September 2010
> Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
> diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
> index f42044d9711c..8dc1235b9784 100644
> --- a/drivers/base/power/sysfs.c
> +++ b/drivers/base/power/sysfs.c
> @@ -357,6 +357,25 @@ static ssize_t wakeup_count_show(struct device *dev,
>
> static DEVICE_ATTR_RO(wakeup_count);
>
> +static ssize_t wakeup_event_count_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + unsigned long count = 0;
> + bool enabled = false;
> +
> + spin_lock_irq(&dev->power.lock);
> + if (dev->power.wakeup) {
> + count = dev->power.wakeup->event_count;
> + enabled = true;
> + }
> + spin_unlock_irq(&dev->power.lock);

Why do you need to lock? The state and count can change right after the
lock, so what does this help with?

> + return enabled ? sprintf(buf, "%lu\n", count) : sprintf(buf, "\n");

Use a real if statement please.

> +}
> +
> +static DEVICE_ATTR_RO(wakeup_event_count);
> +
> +
> +

too many empty lines :)

thanks,

greg k-h

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