linux-kernel - Re: [PATCH v1] PM: runtime: Add support to disable wakeup sources

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Date:   Sun, 21 Aug 2022 16:03:40 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Vimal Kumar <vimal.kumar32@...il.com>
Cc:     chinmoyghosh2001@...il.com, Mintu Patel <mintupatel89@...il.com>,
        Vishal Badole <badolevishal1116@...il.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] PM: runtime: Add support to disable wakeup sources

On Sun, Aug 21, 2022 at 07:15:32PM +0530, Vimal Kumar wrote:
> User could find many wakeup sources available in the bsp, which
> they won't be using. Currently users can only get the status and
> list of enabled wakeup sources, but users can't disable it runtime.
> It's very difficult to find the driver for each wakeup sources from
> where it's getting enabled and make the changes for disabling it.
> 
> This will help users to disable any wakeup sources at runtime,
> avoiding any code change and re-compilation. A new class attribute
> "disable_ws" will be added in the wakeup calss. If user want to disable
> any wakeup sources, user need to find the wakeup dev node associated
> with the particular wakeup source and write the devnode name to the
> class attribute "disable_ws".
> 
> Example:
> Need to disable the wakeup source '1c08000.qcom,pcie'. The dev node
> associated with this wakeup source is:
> cat /sys/class/wakeup3/name ==> "1c08000.qcom,pcie", then for disabling
> this wakeup source :
> 	echo wakeup3 > /sys/class/wakeup/disable_ws
> 
> Co-developed-by: Mintu Patel <mintupatel89@...il.com>
> Signed-off-by: Mintu Patel <mintupatel89@...il.com>
> Co-developed-by: Vishal Badole <badolevishal1116@...il.com>
> Signed-off-by: Vishal Badole <badolevishal1116@...il.com>
> Signed-off-by: Vimal Kumar <vimal.kumar32@...il.com>
> ---
>  drivers/base/power/wakeup_stats.c | 63 ++++++++++++++++++++++++++++++-
>  1 file changed, 62 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/power/wakeup_stats.c b/drivers/base/power/wakeup_stats.c
> index 924fac493c4f..ad30e97f168b 100644
> --- a/drivers/base/power/wakeup_stats.c
> +++ b/drivers/base/power/wakeup_stats.c
> @@ -15,6 +15,7 @@
>  #include <linux/kobject.h>
>  #include <linux/slab.h>
>  #include <linux/timekeeping.h>
> +#include <linux/uaccess.h>
>  
>  #include "power.h"
>  
> @@ -208,9 +209,69 @@ void wakeup_source_sysfs_remove(struct wakeup_source *ws)
>  	device_unregister(ws->dev);
>  }
>  
> +static ssize_t disable_ws_store(struct class *class,
> +				struct class_attribute *attr,
> +				const char *buf, size_t len)
> +{
> +	struct device		*dev;
> +	struct wakeup_source	*ws;
> +	char                    *ws_name;
> +	int                     status;

Please don't pad these out to be in line like this, one space is all
that is needed.

> +
> +	ws_name = kzalloc(sizeof(*(buf)), GFP_KERNEL);

Are you sure this does what you think it does?  You are allocating 8
bytes?

> +	if (!ws_name)
> +		return -ENOMEM;
> +
> +	if (copy_from_user(ws_name, buf, sizeof(*(buf))))

Why are you doing this in a sysfs callback?

Did you test this code?  How?  Can you provide a test script for it
also?

This does not look correct at all :(

thanks,

greg k-h