Re: [PATCH] PCI / PM: Check device_may_wakeup() in pci_enable_wake()

[Bjorn Helgaas]

On Wed, May 09, 2018 at 12:18:32AM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> 
> Commit 0847684cfc5f0 (PCI / PM: Simplify device wakeup settings code)
> went too far and dropped the device_may_wakeup() check from
> pci_enable_wake() which causes wakeup to be enabled during system
> suspend, hibernation or shutdown for some PCI devices that are not
> allowed by user space to wake up the system from sleep (or power off).
> 
> As a result of this excessive power is drawn by some of the affected
> systems while in sleep states or off.
> 
> Restore the device_may_wakeup() check in pci_enable_wake(), but make
> sure that the PCI bus type's runtime suspend callback will not call
> device_may_wakeup() which is about system wakeup from sleep and not
> about device wakeup from runtime suspend.
> 
> Fixes: 0847684cfc5f0 (PCI / PM: Simplify device wakeup settings code)
> Reported-by: Joseph Salisbury <joseph.salisbury@xxxxxxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

0847684cfc5f0 appeared in v4.13, which raises the question of whether
this problem is important enough for a stable backport.  Up to you :)

> ---
>  drivers/pci/pci.c |   29 +++++++++++++++++++++++------
>  1 file changed, 23 insertions(+), 6 deletions(-)
> 
> Index: linux-pm/drivers/pci/pci.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/pci.c
> +++ linux-pm/drivers/pci/pci.c
> @@ -1910,7 +1910,7 @@ void pci_pme_active(struct pci_dev *dev,
>  EXPORT_SYMBOL(pci_pme_active);
>  
>  /**
> - * pci_enable_wake - enable PCI device as wakeup event source
> + * __pci_enable_wake - enable PCI device as wakeup event source
>   * @dev: PCI device affected
>   * @state: PCI state from which device will issue wakeup events
>   * @enable: True to enable event generation; false to disable
> @@ -1928,7 +1928,7 @@ EXPORT_SYMBOL(pci_pme_active);
>   * Error code depending on the platform is returned if both the platform and
>   * the native mechanism fail to enable the generation of wake-up events
>   */
> -int pci_enable_wake(struct pci_dev *dev, pci_power_t state, bool enable)
> +static int __pci_enable_wake(struct pci_dev *dev, pci_power_t state, bool enable)
>  {
>  	int ret = 0;
>  
> @@ -1969,6 +1969,23 @@ int pci_enable_wake(struct pci_dev *dev,
>  
>  	return ret;
>  }
> +
> +/**
> + * pci_enable_wake - change wakeup settings for a PCI device
> + * @pci_dev: Target device
> + * @state: PCI state from which device will issue wakeup events
> + * @enable: Whether or not to enable event generation
> + *
> + * If @enable is set, check device_may_wakeup() for the device before calling
> + * __pci_enable_wake() for it.
> + */
> +int pci_enable_wake(struct pci_dev *pci_dev, pci_power_t state, bool enable)
> +{
> +	if (enable && !device_may_wakeup(&pci_dev->dev))
> +		return -EINVAL;
> +
> +	return __pci_enable_wake(pci_dev, state, enable);
> +}
>  EXPORT_SYMBOL(pci_enable_wake);
>  
>  /**
> @@ -1981,9 +1998,9 @@ EXPORT_SYMBOL(pci_enable_wake);
>   * should not be called twice in a row to enable wake-up due to PCI PM vs ACPI
>   * ordering constraints.
>   *
> - * This function only returns error code if the device is not capable of
> - * generating PME# from both D3_hot and D3_cold, and the platform is unable to
> - * enable wake-up power for it.
> + * This function only returns error code if the device is not allowed to wake
> + * up the system from sleep or it is not capable of generating PME# from both
> + * D3_hot and D3_cold and the platform is unable to enable wake-up power for it.
>   */
>  int pci_wake_from_d3(struct pci_dev *dev, bool enable)
>  {
> @@ -2114,7 +2131,7 @@ int pci_finish_runtime_suspend(struct pc
>  
>  	dev->runtime_d3cold = target_state == PCI_D3cold;
>  
> -	pci_enable_wake(dev, target_state, pci_dev_run_wake(dev));
> +	__pci_enable_wake(dev, target_state, pci_dev_run_wake(dev));
>  
>  	error = pci_set_power_state(dev, target_state);
>  
>