Re: PCI/ASPM locking regression in 6.7-final (was: Re: [PATCH] Revert "PCI/ASPM: Remove pcie_aspm_pm_state_change()")

Johan Hovold
2024-01-30T10:07:50Z

On Wed, Jan 24, 2024 at 09:16:38AM +0100, Johan Hovold wrote:
> On Tue, Jan 23, 2024 at 04:36:48PM -0600, Bjorn Helgaas wrote:

> > I don't quite follow. By simply reverting, do you mean to revert
> > f93e71aea6c6 ("Revert "PCI/ASPM: Remove
> > pcie_aspm_pm_state_change()"")? IIUC that would break Michael's
> > machine again.
>
> Right, at least until that issue is fully understood and alternative
> fixes have been considered.
>
> If that's not an option, we need to rework core to pass a flag through
> more than one layer to indicate whether pcie_aspm_pm_state_change()
> should take the bus semaphore or not. I'd rather not do that if it can
> be avoided.

As a revert appears unlikely to happen, let's fix the regression by
adding a new helper pci_set_power_state_locked() that can be called
with the bus lock held:

https://lore.kernel.org/lkml/20240130100243.11011-1-johan+linaro@kernel.org/

Johan