Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755588AbZCRK6h (ORCPT ); Wed, 18 Mar 2009 06:58:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753566AbZCRK6Z (ORCPT ); Wed, 18 Mar 2009 06:58:25 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:44015 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752790AbZCRK6Y (ORCPT ); Wed, 18 Mar 2009 06:58:24 -0400 Subject: Re: [PATCH] posixtimers: Fix posix clock monotonicity v2 From: Peter Zijlstra To: Hidetoshi Seto Cc: linux-kernel@vger.kernel.org, stable@kernel.org, Ingo Molnar In-Reply-To: <49C0CFC2.7080604@jp.fujitsu.com> References: <49BF3F73.5090007@jp.fujitsu.com> <49C0CFC2.7080604@jp.fujitsu.com> Content-Type: text/plain Date: Wed, 18 Mar 2009 11:58:07 +0100 Message-Id: <1237373887.5069.203.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.25.92 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1214 Lines: 33 On Wed, 2009-03-18 at 19:41 +0900, Hidetoshi Seto wrote: > Impact: Regression fix (against clock_gettime() backwarding bug) > > This patch re-introduces a couple of function, task_sched_runtime > and thread_group_sched_runtime, which was once removed at the > time of 2.6.28-rc1. > > These functions protect the sampling of thread/process clock with > rq lock. This rq lock is required not to update rq->clock durling > the sampling. > i.e. > The clock_gettime() may return > ((accounted runtime before update) + (delta after update)) > that is less than what it should be. > > v1 -> v2: > - Revises comments for functions and patch description. > - Add note about accuracy of thread group's runtime. > > Signed-off-by: Hidetoshi Seto > Cc: Peter Zijlstra > Cc: Ingo Molnar > Cc: stable@kernel.org [2.6.28.x] Acked-by: Peter Zijlstra Thanks Hidetoshi-san. -- 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/