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authorChang-An Chen <chang-an.chen@mediatek.com>2019-03-29 10:59:09 +0800
committerThomas Gleixner <tglx@linutronix.de>2019-04-18 14:34:53 +0200
commit3f2552f7e9c5abef2775c53f7af66532f8bf65bc (patch)
tree72ecad8294d9fd9c351feda420c37d769cb7bebd /kernel/time
parent1c09099188501fd9185b58e79f7c46a15301582c (diff)
downloadlinux-3f2552f7e9c5abef2775c53f7af66532f8bf65bc.tar.bz2
timers/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@mediatek.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Kees Cook <keescook@chromium.org> Cc: Corey Minyard <cminyard@mvista.com> Cc: <linux-mediatek@lists.infradead.org> Cc: <linux-arm-kernel@lists.infradead.org> Cc: Stanley Chu <stanley.chu@mediatek.com> Cc: <kuohong.wang@mediatek.com> Cc: <freddy.hsin@mediatek.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1553828349-8914-1-git-send-email-chang-an.chen@mediatek.com
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/sched_clock.c4
-rw-r--r--kernel/time/tick-common.c2
-rw-r--r--kernel/time/timekeeping.h7
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);