Hi, Some device drivers register CPU hotplug notifiers and use them to destroy device objects when removing the corresponding CPUs and to create these objects when adding the CPUs back. Unfortunately, this is not the right thing to do during suspend/hibernation, since in that cases the CPU hotplug notifiers are called after suspending devices and before resuming them, so the operations in question are carried out on the objects representing suspended devices which shouldn't be unregistered behing the PM core's back. Although right now it usually doesn't lead to any practical complications, it will predictably deadlock if gregkh-driver-pm-acquire-device-locks-prior-to-suspending.patch is applied. The solution is to prevent drivers from removing/adding devices from within CPU hotplug notifiers during suspend/hibernation using the FROZEN bit in the notifier's action argument. However, this has to be done with care, since the devices objects related to the nonboot CPUs that failed to go online during resume should not be present in the system. For this reason, it seems reasonable to introduce a mechanism allowing drivers to ask the PM core to remove device objects corresponding to suspended devices on their behalf. The first patch in the series introduces such a mechanism. The remaining three patches modify the MSR, x86-64 MCE and cpuid drivers in accordance with the above approach. Thanks, Rafael - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
