From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756411AbaHHVMX (ORCPT ); Fri, 8 Aug 2014 17:12:23 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:41143 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932740AbaHHUwY (ORCPT ); Fri, 8 Aug 2014 16:52:24 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Stephen Boyd , John Stultz , Ingo Molnar , Thomas Gleixner , Kamal Mostafa Subject: [PATCH 3.13 186/259] sched_clock: Avoid corrupting hrtimer tree during suspend Date: Fri, 8 Aug 2014 13:40:09 -0700 Message-Id: <1407530482-4483-187-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1407530482-4483-1-git-send-email-kamal@canonical.com> References: <1407530482-4483-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.6 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Stephen Boyd commit f723aa1817dd8f4fe005aab52ba70c8ab0ef9457 upstream. During suspend we call sched_clock_poll() to update the epoch and accumulated time and reprogram the sched_clock_timer to fire before the next wrap-around time. Unfortunately, sched_clock_poll() doesn't restart the timer, instead it relies on the hrtimer layer to do that and during suspend we aren't calling that function from the hrtimer layer. Instead, we're reprogramming the expires time while the hrtimer is enqueued, which can cause the hrtimer tree to be corrupted. Furthermore, we restart the timer during suspend but we update the epoch during resume which seems counter-intuitive. Let's fix this by saving the accumulated state and canceling the timer during suspend. On resume we can update the epoch and restart the timer similar to what we would do if we were starting the clock for the first time. Fixes: a08ca5d1089d "sched_clock: Use an hrtimer instead of timer" Signed-off-by: Stephen Boyd Signed-off-by: John Stultz Link: http://lkml.kernel.org/r/1406174630-23458-1-git-send-email-john.stultz@linaro.org Cc: Ingo Molnar Signed-off-by: Thomas Gleixner Signed-off-by: Kamal Mostafa --- kernel/time/sched_clock.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c index 0abb364..4763ec7 100644 --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -192,7 +192,8 @@ void __init sched_clock_postinit(void) static int sched_clock_suspend(void) { - sched_clock_poll(&sched_clock_timer); + update_sched_clock(); + hrtimer_cancel(&sched_clock_timer); cd.suspended = true; return 0; } @@ -200,6 +201,7 @@ static int sched_clock_suspend(void) static void sched_clock_resume(void) { cd.epoch_cyc = read_sched_clock(); + hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); cd.suspended = false; } -- 1.9.1