mutex(9) on sparc64 RMO [was Re: pserialize(9) vs. TAILQ]

[Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost>]

   Date: Mon, 24 Nov 2014 16:44:41 +0000 (UTC)
   From: Eduardo Horvath <eeh%NetBSD.org@localhost>

   I enhanced membar_ops with proper memory barriers and then was looking at 
   the mutex code.  Unfortunately, I didn't get very far.  It seemed at the 
   time that the mutex code has two hooks for memory barriers after the 
   atomic operations, however it's missing memory barrier hooks to ensure 
   consistency before accessing the lock.

What exactly is the consistency you need before accessing the lock?