On Tue, 25 Mar 2008, Rafael J. Wysocki wrote: > > I just thought of another problem. At the point where > > local_irq_disable() is called, in between device_suspend() and > > device_power_down(), it is possible in a preemptible kernel that > > another task is holding dpm_list_mtx and is in the middle of updating > > the list pointers. This would mess up the traversal in > > device_power_down(). > > > > I'm not sure about the best way to prevent this. Is it legal to call > > unlock_mutex() while interrupts or preemption are disabled? > > Well, I think it is, but I'm not sure how that can help. > > To prevent the race from happening, we can lock dpm_list_mtx before switching > interrupts off in kernel/power/main.c:suspend_enter() and analogously in > kernel/power/disk.c . That's right. And once interrupts are turned off you should unlock dpm_list_mtx again, in case a noirq method wants to unregister a device. Hence my question: Is it legal to call unlock_mutex() while interrupts are disabled? Alan Stern -- 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
