On Wed, 05 Sep 2012 14:04:25 +0200, Michael Lawnick wrote: > Documentation originally recommends to use an enum. > This is not applicable for a tree with unlimited depth. > This is why I use the adapter id which is expected > to be unique and monotonic increasing with the depth of > the tree. For the records, "monotonic increasing with the depth of the tree" isn't guaranteed. It is generally true, but with i2c adapter removal and hot-plugging, it can happen that an adapter has a lower id than its parent. For example: * Register adapters 0, 1 and 2. * Remove adapter 1. * Instantiate a multiplexer on bus 2. The first child adapter will get number 1, and 1 < 2. That being said, after looking at the code, I don't think lockdep cares about locks with lower class being taken first. OTOH it cares about locking order being always the same, and with i2c adapters coming and going, this would have been impossible to guarantee with your first implementation (although I very much doubt this would have been a problem in practice.) Of course these points are all moot anyway as we have a better implementation which (hopefully) doesn't suffer from any of the problems yours had. -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
