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timers/sched_clock: Prevent generic sched_clock wrap caused by tick_freeze() 

tick_freeze() introduced by suspend-to-idle in commit 124cf9117c ("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: 124cf9117c (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
This commit is contained in:
Chang-An Chen 2019-03-29 10:59:09 +08:00 committed by Thomas Gleixner
parent 1c09099188
commit 3f2552f7e9
3 changed files with 11 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
kernel/time/sched_clock.c
View File

@ -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];

2
kernel/time/tick-common.c
View File

@ -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);

7
kernel/time/timekeeping.h
View File

@ -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);