On Fri, 2009-08-07 at 12:45 -0400, Alan Stern wrote: > On Fri, 7 Aug 2009, Peter Zijlstra wrote: > > The other proposal was creating a fixed list of classes and register > > each device at a class corresponding to its depth in the tree. I can't > > remember what was wrong with that, but I seem to have been persuaded > > that that was hard too. > > It probably would work for the most part. However a possible scenario > involves first locking a parent and then locking all its children. (I > don't know if this ever happens anywhere, but it might.) This can't > cause a deadlock but it would run into trouble with depth-based > classes. If you know which parent is locked, we can solve that with mutex_lock_nest_lock() [ doesn't currently exist, but is analogous to spin_lock_nest_lock() ] and together with http://lkml.org/lkml/2009/7/23/222 that would allow you to lock up to 2048 children. Would something like that work? -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
