On Fri, 2008-01-18 at 14:29 -0800, David Brownell wrote: > EXPERIMENTAL and incomplete patch to make LOCKDEP behave better in > the face of irq chaining, by annotating irqs with a lock_class which > can reflect that hierarchy.
This is too short for me (who has no clue about genirq) to understand what this patch does or why it does it. > This version of the patch is incomplete in at least two respects: > > - There's no spin_lock_irq_nested() primitive, so that locking calls > on irq probing (yeech!) paths must ignore the annotations. > > ==> LOCKDEP feature is evidently missing: > spin_lock_irq_nested(lock_ptr, lock_class) This rant is more lines than adding the API :-/ the reason for it not being there is simple, it wasn't needed up until now. > - We'd really need new API to declare the parent/child relationships > between IRQs to handle this properly. Lacking such calls, this just > piggybacks set_irq_chained_handler() to modify the parent's class. > That's a problem, since only the lowest level of any lock tree gets > accurate nesting annotations. On the plus side: no platform changes > are needed this way, so testing is easy. > > ==> GENIRQ programming interface evidently missing > set_irq_parent(parent_irqnum, child_irqnum) (?) > > Example: when a GPIO controller's set_wake() handler needs to call its > parent's set_irq_wake() method to ensure all appropriate signal paths are > set up, that currently generates a bogus lockdep warning. This patch > removes those bogus warnings ... when there's only one level of parent. OK.... still need a bit more detail here. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
