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Message-ID: <tip-fe4a9a665de982b9eeb4a5e61f9c1c1abe80fb51@git.kernel.org> Date: Thu, 18 Apr 2019 05:19:08 -0700 From: tip-bot for Chang-An Chen <tipbot@...or.com> To: linux-tip-commits@...r.kernel.org Cc: freddy.hsin@...iatek.com, kuohong.wang@...iatek.com, chang-an.chen@...iatek.com, hpa@...or.com, keescook@...omium.org, linux-kernel@...r.kernel.org, mingo@...nel.org, matthias.bgg@...il.com, tglx@...utronix.de, cminyard@...sta.com, john.stultz@...aro.org, linux-mediatek@...ts.infradead.org, stanley.chu@...iatek.com, linux-arm-kernel@...ts.infradead.org, fweisbec@...il.com Subject: [tip:timers/urgent] tiemrs/sched_clock: Prevent generic sched_clock wrap caused by tick_freeze() Commit-ID: fe4a9a665de982b9eeb4a5e61f9c1c1abe80fb51 Gitweb: https://git.kernel.org/tip/fe4a9a665de982b9eeb4a5e61f9c1c1abe80fb51 Author: Chang-An Chen <chang-an.chen@...iatek.com> AuthorDate: Fri, 29 Mar 2019 10:59:09 +0800 Committer: Thomas Gleixner <tglx@...utronix.de> CommitDate: Thu, 18 Apr 2019 14:16:31 +0200 tiemrs/sched_clock: Prevent generic sched_clock wrap caused by tick_freeze() tick_freeze() introduced by suspend-to-idle in commit 124cf9117c5f ("PM / sleep: Make it possible to quiesce timers during suspend-to-idle") uses timekeeping_suspend() instead of syscore_suspend() during suspend-to-idle. As a consequence generic sched_clock will keep going because sched_clock_suspend() and sched_clock_resume() are not invoked during suspend-to-idle which can result in a generic sched_clock wrap. On a ARM system with suspend-to-idle enabled, sched_clock is registered as "56 bits at 13MHz, resolution 76ns, wraps every 4398046511101ns", which means the real wrapping duration is 8796093022202ns. [ 134.551779] suspend-to-idle suspend (timekeeping_suspend()) [ 1204.912239] suspend-to-idle resume (timekeeping_resume()) ...... [ 1206.912239] suspend-to-idle suspend (timekeeping_suspend()) [ 5880.502807] suspend-to-idle resume (timekeeping_resume()) ...... [ 6000.403724] suspend-to-idle suspend (timekeeping_suspend()) [ 8035.753167] suspend-to-idle resume (timekeeping_resume()) ...... [ 8795.786684] (2)[321:charger_thread]...... [ 8795.788387] (2)[321:charger_thread]...... [ 0.057226] (0)[0:swapper/0]...... [ 0.061447] (2)[0:swapper/2]...... sched_clock was not stopped during suspend-to-idle, and sched_clock_poll hrtimer was not expired because timekeeping_suspend() was invoked during suspend-to-idle. It makes sched_clock wrap at kernel time 8796s. To prevent this, invoke sched_clock_suspend() and sched_clock_resume() in tick_freeze() together with timekeeping_suspend() and timekeeping_resume(). Fixes: 124cf9117c5f (PM / sleep: Make it possible to quiesce timers during suspend-to-idle) Signed-off-by: Chang-An Chen <chang-an.chen@...iatek.com> Signed-off-by: Thomas Gleixner <tglx@...utronix.de> Cc: Frederic Weisbecker <fweisbec@...il.com> Cc: Matthias Brugger <matthias.bgg@...il.com> Cc: John Stultz <john.stultz@...aro.org> Cc: Kees Cook <keescook@...omium.org> Cc: Corey Minyard <cminyard@...sta.com> Cc: <linux-mediatek@...ts.infradead.org> Cc: <linux-arm-kernel@...ts.infradead.org> Cc: Stanley Chu <stanley.chu@...iatek.com> Cc: <kuohong.wang@...iatek.com> Cc: <freddy.hsin@...iatek.com> Cc: stable@...r.kernel.org Link: https://lkml.kernel.org/r/1553828349-8914-1-git-send-email-chang-an.chen@mediatek.com --- kernel/time/sched_clock.c | 4 ++-- kernel/time/tick-common.c | 2 ++ kernel/time/timekeeping.h | 7 +++++++ 3 files changed, 11 insertions(+), 2 deletions(-) diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c index 094b82ca95e5..930113b9799a 100644 --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -272,7 +272,7 @@ static u64 notrace suspended_sched_clock_read(void) return cd.read_data[seq & 1].epoch_cyc; } -static int sched_clock_suspend(void) +int sched_clock_suspend(void) { struct clock_read_data *rd = &cd.read_data[0]; @@ -283,7 +283,7 @@ static int sched_clock_suspend(void) return 0; } -static void sched_clock_resume(void) +void sched_clock_resume(void) { struct clock_read_data *rd = &cd.read_data[0]; diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c index 529143b4c8d2..df401463a191 100644 --- a/kernel/time/tick-common.c +++ b/kernel/time/tick-common.c @@ -487,6 +487,7 @@ void tick_freeze(void) trace_suspend_resume(TPS("timekeeping_freeze"), smp_processor_id(), true); system_state = SYSTEM_SUSPEND; + sched_clock_suspend(); timekeeping_suspend(); } else { tick_suspend_local(); @@ -510,6 +511,7 @@ void tick_unfreeze(void) if (tick_freeze_depth == num_online_cpus()) { timekeeping_resume(); + sched_clock_resume(); system_state = SYSTEM_RUNNING; trace_suspend_resume(TPS("timekeeping_freeze"), smp_processor_id(), false); diff --git a/kernel/time/timekeeping.h b/kernel/time/timekeeping.h index 7a9b4eb7a1d5..141ab3ab0354 100644 --- a/kernel/time/timekeeping.h +++ b/kernel/time/timekeeping.h @@ -14,6 +14,13 @@ extern u64 timekeeping_max_deferment(void); extern void timekeeping_warp_clock(void); extern int timekeeping_suspend(void); extern void timekeeping_resume(void); +#ifdef CONFIG_GENERIC_SCHED_CLOCK +extern int sched_clock_suspend(void); +extern void sched_clock_resume(void); +#else +static inline int sched_clock_suspend(void) { return 0; } +static inline void sched_clock_resume(void) { } +#endif extern void do_timer(unsigned long ticks); extern void update_wall_time(void);
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