Re: [PATCH v15 3/7] PCI: Fail FLR when config space is inaccessible

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Logic flaw: pci_dev_config_accessible() executed before the probe check can permanently disable the FLR capability.
--

commit dc74511c4dd4719d1b362bacdaab4c551ada9e66
Author: Farhan Ali <alifm@linux.ibm.com>

PCI: Fail FLR when config space is inaccessible

This commit adds a check to validate if a device's config space is accessible
before attempting an FLR reset. This is intended to fail the FLR early when
the device is in an error state.

> If a device is in an error state, then it's config space may not be
> accssible.

This isn't a bug, but there are a couple of typos here ("it's" instead of
"its", and "accssible" instead of "accessible").

> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index e71b814153921..c50418f5e3181 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4396,6 +4396,9 @@ int pcie_reset_flr(struct pci_dev *dev, bool probe)
>  	if (!(dev->devcap & PCI_EXP_DEVCAP_FLR))
>  		return -ENOTTY;
>  
> +	if (!pci_dev_config_accessible(dev, "FLR"))
> +		return -ENOTTY;
> +
>  	if (probe)
>  		return 0;

Could this placement cause the FLR capability to be permanently disabled if
the device is temporarily inaccessible during discovery?

pcie_reset_flr() is called with probe == true during device initialization
to discover if the hardware inherently supports FLR. By placing the live
config space check before the probe check, the system will actively read the
PCI_COMMAND register during capability discovery.

If the device happens to be temporarily inaccessible during this probe phase,
it will return -ENOTTY and FLR will be permanently omitted from the device's
reset_methods array.

Would it make sense to move the pci_dev_config_accessible() check after the
if (probe) block so we only check accessibility when actually performing the
reset?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260505200510.2954-1-alifm@linux.ibm.com?part=3