From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423218AbbD2NmX (ORCPT ); Wed, 29 Apr 2015 09:42:23 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:55905 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1422935AbbD2NmS (ORCPT ); Wed, 29 Apr 2015 09:42:18 -0400 From: "Rafael J. Wysocki" To: Sudeep Holla , Peter Zijlstra , Linus Walleij , Daniel Lezcano Cc: "Rafael J. Wysocki" , Linux PM list , Thomas Gleixner , Ingo Molnar , Linux Kernel Mailing List , ACPI Devel Maling List Subject: [PATCH][Fix] cpuidle: Run tick_broadcast_exit() with disabled interrupts Date: Wed, 29 Apr 2015 16:07:10 +0200 Message-ID: <2872649.RClMYKns0i@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.0.0+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <5540A981.6060209@arm.com> References: <2112147.0kYCHhbEJT@vostro.rjw.lan> <6185796.9I7OmaAAcQ@vostro.rjw.lan> <5540A981.6060209@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki Commit 335f49196fd6 (sched/idle: Use explicit broadcast oneshot control function) replaced clockevents_notify() invocations in cpuidle_idle_call() with direct calls to tick_broadcast_enter() and tick_broadcast_exit(), but it overlooked the fact that interrupts were already enabled before calling the latter which led to functional breakage on systems using idle states with the CPUIDLE_FLAG_TIMER_STOP flag set. Fix that by moving the invocations of tick_broadcast_enter() and tick_broadcast_exit() down into cpuidle_enter_state() where interrupts are still disabled when tick_broadcast_exit() is called. Also ensure that interrupts will be disabled before running tick_broadcast_exit() even if they have been enabled by the idle state's ->enter callback. Trigger a WARN_ON_ONCE() in that case, as we generally don't want that to happen for states with CPUIDLE_FLAG_TIMER_STOP set. Fixes: 335f49196fd6 (sched/idle: Use explicit broadcast oneshot control function) Reported-and-tested-by: Linus Walleij Acked-by: Peter Zijlstra (Intel) Acked-by: Daniel Lezcano Reported-and-tested-by: Sudeep Holla Signed-off-by: Rafael J. Wysocki --- Thanks for the testing and ACKs, here it goes again with all tags and a changelog. If anything is missing/incorrect, please let me know ASAP as I'm going to push this to Linus in a couple of days. --- drivers/cpuidle/cpuidle.c | 16 ++++++++++++++++ kernel/sched/idle.c | 16 ++-------------- 2 files changed, 18 insertions(+), 14 deletions(-) Index: linux-pm/kernel/sched/idle.c =================================================================== --- linux-pm.orig/kernel/sched/idle.c +++ linux-pm/kernel/sched/idle.c @@ -81,7 +81,6 @@ static void cpuidle_idle_call(void) struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); int next_state, entered_state; - unsigned int broadcast; bool reflect; /* @@ -150,17 +149,6 @@ static void cpuidle_idle_call(void) goto exit_idle; } - broadcast = drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP; - - /* - * Tell the time framework to switch to a broadcast timer - * because our local timer will be shutdown. If a local timer - * is used from another cpu as a broadcast timer, this call may - * fail if it is not available - */ - if (broadcast && tick_broadcast_enter()) - goto use_default; - /* Take note of the planned idle state. */ idle_set_state(this_rq(), &drv->states[next_state]); @@ -174,8 +162,8 @@ static void cpuidle_idle_call(void) /* The cpu is no longer idle or about to enter idle. */ idle_set_state(this_rq(), NULL); - if (broadcast) - tick_broadcast_exit(); + if (entered_state == -EBUSY) + goto use_default; /* * Give the governor an opportunity to reflect on the outcome Index: linux-pm/drivers/cpuidle/cpuidle.c =================================================================== --- linux-pm.orig/drivers/cpuidle/cpuidle.c +++ linux-pm/drivers/cpuidle/cpuidle.c @@ -158,9 +158,18 @@ int cpuidle_enter_state(struct cpuidle_d int entered_state; struct cpuidle_state *target_state = &drv->states[index]; + bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP); ktime_t time_start, time_end; s64 diff; + /* + * Tell the time framework to switch to a broadcast timer because our + * local timer will be shut down. If a local timer is used from another + * CPU as a broadcast timer, this call may fail if it is not available. + */ + if (broadcast && tick_broadcast_enter()) + return -EBUSY; + trace_cpu_idle_rcuidle(index, dev->cpu); time_start = ktime_get(); @@ -169,6 +178,13 @@ int cpuidle_enter_state(struct cpuidle_d time_end = ktime_get(); trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); + if (broadcast) { + if (WARN_ON_ONCE(!irqs_disabled())) + local_irq_disable(); + + tick_broadcast_exit(); + } + if (!cpuidle_state_is_coupled(dev, drv, entered_state)) local_irq_enable();