On Fri, Nov 17, 2023 at 04:00:46PM -0800, David E. Box wrote: > On Tue, 2023-11-14 at 14:55 +0100, Johan Hovold wrote: > > Add a helper for enabling link states that can be used in contexts where > > a pci_bus_sem read lock is already held (e.g. from pci_walk_bus()). > > > > This helper will be used to fix a couple of potential deadlocks where > > the current helper is called with the lock already held, hence the CC > > stable tag. > This solution is similar to the original one I proposed [1]. It just creates a > separate locked function rather than using a flag. While the API is consistent > with pci_disable_link_state_locked(), its usage is not. The vmd driver calls > pci_enable_link_state() from pci_walk_bus() which was problematic for Bjorn [2]. > I owed an attempt to implement this as a fixup. However, now > qcom_pcie_enabled_aspm() is also using it from pci_walk_bus(). The fixup could > make sense for VMD since there it's fixing missing BIOS settings, but I'm not > sure about qcom. Bjorn, do you still see issues with the use in pci_bus_walk()? We need this for Qualcomm platforms where the boot firmware does not enable ASPM, and the hotplug inconsistency was also discussed with Bjorn here: https://lore.kernel.org/linux-pci/20231018164731.GA1365588@bhelgaas/ > [1] > https://lore.kernel.org/lkml/20230321233849.3408339-1-david.e.box@xxxxxxxxxxxxxxx/ > > [2] https://lore.kernel.org/lkml/20230322205702.GA2493123@bhelgaas/ Johan
