Re: [PATCH] PCI/AER: Stop ruling out unbound devices as error source

[Bjorn Helgaas <helgaas@kernel.org>]

On Fri, Mar 27, 2026 at 10:56:43AM +0100, Lukas Wunner wrote:
> When searching for the error source, the AER driver rules out devices
> whose enable_cnt is zero.  This was introduced in 2009 by commit
> 28eb27cf0839 ("PCI AER: support invalid error source IDs") without
> providing a rationale.
> 
> Drivers typically call pci_enable_device() on probe, hence the enable_cnt
> check essentially filters out unbound devices.  At the time of the commit,
> drivers had to opt in to AER by calling pci_enable_pcie_error_reporting()
> and so any AER-enabled device could be assumed to be bound to a driver.
> The check thus made sense because it allowed skipping config space
> accesses to devices which were known not to be the error source.
> 
> But since 2022, AER is universally enabled on all devices when they are
> enumerated, cf. commit f26e58bf6f54 ("PCI/AER: Enable error reporting when
> AER is native").
> 
> Errors may very well be reported by unbound devices, e.g. due to link
> instability.  By ruling them out as error source, errors reported by them
> are neither logged nor cleared.  When they do get bound and another error
> occurs, the earlier error is reported together with the new error, which
> may confuse users.  Stop doing so.
> 
> Fixes: f26e58bf6f54 ("PCI/AER: Enable error reporting when AER is native")
> Signed-off-by: Lukas Wunner <lukas@wunner.de>
> Cc: stable@vger.kernel.org # v6.0+

Applied to pci/aer for v7.1, thanks!

> ---
>  drivers/pci/pcie/aer.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index 4299c55..384d026 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -1039,8 +1039,6 @@ static bool is_error_source(struct pci_dev *dev, struct aer_err_info *e_info)
>  	 *      3) There are multiple errors and prior ID comparing fails;
>  	 * We check AER status registers to find possible reporter.
>  	 */
> -	if (atomic_read(&dev->enable_cnt) == 0)
> -		return false;
>  
>  	/* Check if AER is enabled */
>  	pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &reg16);
> -- 
> 2.51.0
>