Re: [PATCH v2] PM: sleep: core: Avoid setting power.must_resume to false

[Greg KH]

On Sun, Aug 08, 2021 at 09:10:27AM -0700, Prasad Sodagudi wrote:
> There are variables(power.may_skip_resume and dev->power.must_resume)
> and DPM_FLAG_MAY_SKIP_RESUME flags to control the resume of devices after
> a system wide suspend transition.
> 
> Setting the DPM_FLAG_MAY_SKIP_RESUME flag means that the driver allows
> its "noirq" and "early" resume callbacks to be skipped if the device
> can be left in suspend after a system-wide transition into the working
> state. PM core determines that the driver's "noirq" and "early" resume
> callbacks should be skipped or not with dev_pm_skip_resume() function by
> checking power.may_skip_resume variable.
> 
> power.must_resume variable is getting set to false in __device_suspend()
> function without checking device's DPM_FLAG_MAY_SKIP_RESUME and
> dev->power.usage_count variables. In problematic scenario, where
> all the devices in the suspend_late stage are successful and some
> device can fail to suspend in suspend_noirq phase. So some devices
> successfully suspended in suspend_late stage are not getting chance
> to execute __device_suspend_noirq() to set dev->power.must_resume
> variable to true and not getting resumed in early_resume phase.
> 
> Add a check for device's DPM_FLAG_MAY_SKIP_RESUME flag before
> setting power.must_resume variable in __device_suspend function.
> 
> Fixes: 6e176bf8d461 ("PM: sleep: core: Do not skip callbacks in the resume phase")
> Signed-off-by: Prasad Sodagudi <psodagud@xxxxxxxxxxxxxx>
> ---
>  drivers/base/power/main.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index d568772..9ee6987 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -1642,7 +1642,11 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
>  	}
>  
>  	dev->power.may_skip_resume = true;
> -	dev->power.must_resume = false;
> +	if ((atomic_read(&dev->power.usage_count) <= 1) &&
> +	     (dev_pm_test_driver_flags(dev, DPM_FLAG_MAY_SKIP_RESUME)))
> +		dev->power.must_resume = false;
> +	else
> +		dev->power.must_resume = true;
>  
>  	dpm_watchdog_set(&wd, dev);
>  	device_lock(dev);
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

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