Re: [PATCH 3/4] drm/xe/pm: allow the device to signal PME from D3hot

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The variable `err` is used uninitialized in the warning message when `pci_enable_wake()` fails, potentially leaking stack memory to the kernel log.
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commit 49538b2bae6d5a5f0599da227733b24b63d3639b
Author: Vinod Govindapillai <vinod.govindapillai@intel.com>

    drm/xe/pm: allow the device to signal PME from D3hot
    
    Make the device a usable wakeup source so it can raise PME while runtime
    suspended to D3hot The PCI core marks endpoints wakeup-capable but leaves
    them disabled, so pci_enable_wake() returns -EINVAL until the driver opts
    in using devm_device_init_wakeup(). D3cold is excluded, as the device
    loses power there and cannot signal at all.

> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
> index 3b3b6426d960c..af59859fd8c96 100644
> --- a/drivers/gpu/drm/xe/xe_pci.c
> +++ b/drivers/gpu/drm/xe/xe_pci.c
[ ... ]
> @@ -1380,6 +1384,7 @@ static int xe_pci_runtime_suspend(struct device *dev)
>  {
>  	struct pci_dev *pdev = to_pci_dev(dev);
>  	struct xe_device *xe = pdev_to_xe_device(pdev);
> +	bool pme_armed = false;
>  	int err;
>  
>  	/*
> @@ -1391,9 +1396,20 @@ static int xe_pci_runtime_suspend(struct device *dev)
>  	xe_assert(xe, !IS_SRIOV_VF(xe));
>  	xe_assert(xe, !pci_num_vf(pdev));
>  
> -	err = xe_pm_runtime_suspend(xe, false);
> -	if (err)
> +	if (xe_pm_pme_capable(xe)) {
> +		pme_armed = !pci_enable_wake(pdev, PCI_D3hot, true);
> +		if (!pme_armed)
> +			drm_warn(&xe->drm,
> +				 "Failed to arm PME for D3hot: %d\n", err);

[Severity: Medium]
Could this leak uninitialized stack memory to the kernel log? It looks like
the variable err is used in the warning message when pci_enable_wake() fails
in xe_pci_runtime_suspend(), but it hasn't been initialized yet. Since the
return value from pci_enable_wake() is inverted into the boolean pme_armed,
the actual error code is never captured in err before printing it.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260826225338.804902-1-vinod.govindapillai@intel.com?part=3