On Mon, Jun 05, 2023 at 08:35:45PM +0200, Johannes Berg wrote: > @@ -3139,6 +3139,7 @@ void pci_pm_init(struct pci_dev *dev) > u16 pmc; > > pm_runtime_forbid(&dev->dev); > + pm_runtime_get_noresume(&dev->dev); > pm_runtime_set_active(&dev->dev); > pm_runtime_enable(&dev->dev); > device_enable_async_suspend(&dev->dev); > @@ -335,9 +336,12 @@ void pci_bus_add_device(struct pci_dev *dev) > int retval; > > /* > - * Can not put in pci_device_add yet because resources > - * are not assigned yet for some devices. > + * Allow runtime PM only here, since otherwise we may > + * try to suspend a device that isn't fully configured > + * yet, which causes problems. > */ > + pm_runtime_put_noidle(&dev->dev); > + > pcibios_bus_add_device(dev); > pci_fixup_device(pci_fixup_final, dev); > pci_create_sysfs_dev_files(dev); There seem to be many different callers that end up in pci_pm_init() and pci_bus_add_device(). Is it guaranteed that the two functions are always called in order? Do callers exist which only invoke the former but not the latter or vice-versa? Can it happen that a caller of the former errors out, so the latter is never called, leading to a runtime PM ref imbalance? It would be easier to ascertain correctness if you could find a function at a higher level which (indirectly) calls both pci_pm_init() and pci_bus_add_device() so that you can acquire and release the runtimw PM ref in that single function. Thanks, Lukas
