From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Subject: Re: [RFC patch 08/18] cnt32_to_63 should use smp_rmb() Date: Fri, 07 Nov 2008 10:59:28 +0000 Message-ID: <25275.1226055568@redhat.com> References: <20081106220530.5b0e3a96.akpm@linux-foundation.org> <20081107052336.652868737@polymtl.ca> <20081107053349.861709786@polymtl.ca> Return-path: Received: from mx2.redhat.com ([66.187.237.31]:45898 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751819AbYKGLAB (ORCPT ); Fri, 7 Nov 2008 06:00:01 -0500 In-Reply-To: <20081106220530.5b0e3a96.akpm@linux-foundation.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Andrew Morton Cc: dhowells@redhat.com, Mathieu Desnoyers , Linus Torvalds , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, Nicolas Pitre , Ralf Baechle , benh@kernel.crashing.org, paulus@samba.org, David Miller , Ingo Molnar , Thomas Gleixner , Steven Rostedt , linux-arch@vger.kernel.org Andrew Morton wrote: > I mean, the darned thing is called from sched_clock(), which can be > concurrently called on separate CPUs and which can be called from > interrupt context (with an arbitrary nesting level!) while it was running > in process context. > > Who let that thing into Linux? Having crawled all over it, and argued with Nicolas and Panasonic about it, I think it's safe in sched_clock(), provided sched_clock() never gets preempted - which appears to be the case. David