On Mon, 2005-08-22 at 15:44 -0400, Steven Rostedt wrote: > On Mon, 2005-08-22 at 20:33 +0200, Ingo Molnar wrote: > > > any ideas how to get rid of pi_lock altogether? > > I've toyed with the idea of adding another raw_spin_lock to the mutex. A > lock specific pi_lock. Instead of grabbing a global pi_lock, grab the > pi_lock of a lock. To modify any lock w.r.t PI, you must first grab all > the lock's pi_locks being referenced.
Are you saying that you want to convert the current system to lock all the pi_locks for all the locks in the sequence? It seems like you could make it a per task lock, then only lock the task's pi_lock for pi operations. > The idea stems from the fact that the kernel must order its taking of > locks to prevent deadlocks. This way the order of locks that are taken > are also always in order. > > So if you have the following case: > > P1 blocked_on L1 owned_by P2 blocked_on L2 owned_by P3 ... > > The L1, L2, L3 ... must always be in the same order, otherwise the > kernel itself can have a deadlock. > > OK, let me prove this (for myself as well ;-) > > Lets go by contradiction. Proof seems straight forward enough. One downside would be an increase in mutex structure size though. Daniel - 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/
