From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:40472 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934301AbeCGTkK (ORCPT ); Wed, 7 Mar 2018 14:40:10 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Anna-Maria Gleixner , Christoph Hellwig , John Stultz , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , keescook@chromium.org, Ingo Molnar , Mike Galbraith Subject: [PATCH 4.15 002/122] hrtimer: Ensure POSIX compliance (relative CLOCK_REALTIME hrtimers) Date: Wed, 7 Mar 2018 11:36:54 -0800 Message-Id: <20180307191729.517036716@linuxfoundation.org> In-Reply-To: <20180307191729.190879024@linuxfoundation.org> References: <20180307191729.190879024@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Anna-Maria Gleixner commit 48d0c9becc7f3c66874c100c126459a9da0fdced upstream. The POSIX specification defines that relative CLOCK_REALTIME timers are not affected by clock modifications. Those timers have to use CLOCK_MONOTONIC to ensure POSIX compliance. The introduction of the additional HRTIMER_MODE_PINNED mode broke this requirement for pinned timers. There is no user space visible impact because user space timers are not using pinned mode, but for consistency reasons this needs to be fixed. Check whether the mode has the HRTIMER_MODE_REL bit set instead of comparing with HRTIMER_MODE_ABS. Signed-off-by: Anna-Maria Gleixner Cc: Christoph Hellwig Cc: John Stultz Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: keescook@chromium.org Fixes: 597d0275736d ("timers: Framework for identifying pinned timers") Link: http://lkml.kernel.org/r/20171221104205.7269-7-anna-maria@linutronix.de Signed-off-by: Ingo Molnar Cc: Mike Galbraith Signed-off-by: Greg Kroah-Hartman --- kernel/time/hrtimer.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -1104,7 +1104,12 @@ static void __hrtimer_init(struct hrtime cpu_base = raw_cpu_ptr(&hrtimer_bases); - if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS) + /* + * POSIX magic: Relative CLOCK_REALTIME timers are not affected by + * clock modifications, so they needs to become CLOCK_MONOTONIC to + * ensure POSIX compliance. + */ + if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL) clock_id = CLOCK_MONOTONIC; base = hrtimer_clockid_to_base(clock_id);