Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753527AbYKGLAS (ORCPT ); Fri, 7 Nov 2008 06:00:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751828AbYKGLAE (ORCPT ); Fri, 7 Nov 2008 06:00:04 -0500 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 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20081106220530.5b0e3a96.akpm@linux-foundation.org> References: <20081106220530.5b0e3a96.akpm@linux-foundation.org> <20081107052336.652868737@polymtl.ca> <20081107053349.861709786@polymtl.ca> 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 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> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 763 Lines: 19 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/