On Wed, 10 Sep 2014, Jiang Liu wrote: > On 2014/9/9 20:37, Thomas Gleixner wrote: > >> + ret = mp_ioapic_registered(gsi_base); > >> + up_write(&acpi_ioapic_rwsem); > >> + > >> + return ret; > >> +} > > > > So I assume that this is for a particular caller in the apci ioapic > > hotplug code and that call site has its own serialization. Otherwise > > the return value is not protected at all. > > > > Please add a Docbook comment to that function, and document the > > locking rules as thats pretty non obvious. > How about this comments about locking rules? > /* > * Locks related to IOAPIC hotplug > * Hotplug side: > * ->lock_device_hotplug() //device_hotplug_lock > * ->acpi_ioapic_rwsem > * ->ioapic_lock > * Interrupt mapping side: > * ->acpi_ioapic_rwsem > * ->ioapic_mutex > * ->ioapic_lock > */ That looks asymetric. Why is the hotplug side not taking ioapic_mutex? Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
