On Wed, Sep 02, Peter Zijlstra wrote: > > So the proposal I currently have to solve this is to allocate 48 lock > classes: > > struct lock_class_key device_tree_depth[MAX_LOCK_DEPTH]; > > and when creating a new device node, set the lock class corresponding > the depth in the tree: > > mutex_lock_init(&device->lock); > BUG_ON(device->depth >= MAX_LOCK_DEPTH); // surely we're not that deep > lockdep_set_class(&device->lock, device_tree_depth + device->depth); > ... > mutex_lock(&device->lock); /* already have parent locked */ > device_attach(device, parent); > > and take multiple child locks using: > > mutex_lock_nest_lock(&device->lock, &device->parent->lock); > > Which, I think should work for most cases out there. > > Alan had some funny corner cases, but I think he wasn't sure whether > those would indeed show up in reality. JFYI, I tried to get away with just parent, child and normal class but the problem is that device_add() is called recursive via driver probing code. So either we change that (and iterate down the device tree) or we need to implement what you proposed. Cheers, Jan -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
