On Sat, 5 Sep 2015 08:18:36 -0400 Steven Rostedt <[email protected]> wrote:
> On Sat, 5 Sep 2015 12:30:59 +0200 (CEST) > Thomas Gleixner <[email protected]> wrote: > > > > So instead of doing that proposed magic boost, we can do something > > more straight forward: > > > > retry: > > lock(B); > > if (!try_lock(A)) { > > lock_and_drop(A, B); > > unlock(A); > > goto retry; > > } > > > > lock_and_drop() queues the task as a waiter on A, drops B and then > > does the PI adjustment on A. > > That was my original solution, and I believe I added patches to do > exactly that to the networking code in the past. I remember writing > that helper function such that on non PREEMPT_RT it was a nop. Just to point out again that I misread what you wrote. That's what I get for responding to email 10 minutes after I get out of bed ;-) You need to be careful about adding the waiter on A. If the owner of A is blocked on B, the pi inheritance may detect that as a deadlock. -- Steve -- 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/
