lkml.org 
[lkml]   [2014]   [Sep]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH RESEND] PM / sleep: Fix racing timers
Date
On platforms that do not power off during suspend, successfully entering
suspend races with timers.

The race happening in a couple of location is:

1. disable IRQs (e.g. arch_suspend_disable_irqs())
...
2. syscore_suspend()
-> timekeeping_suspend()
-> clockevents_notify(SUSPEND)
-> tick_suspend() (timers are turned off here)
...
3. wfi (wait for wake-IRQ here)

Between steps 1 and 2 the timers can still generate interrupts that are
not handled and stay pending until step 3. That pending IRQ causes an
immediate - spurious - wake.

The solution is to move the clockevents suspend/resume notification
out of the syscore_suspend step and explictly call them at the appropriate
time in the suspend/hibernation paths. I.e. timers are suspend _before_
IRQs get disabled. And accordingly in the resume path.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
Hi,

there was not a lot of discussion on the last submission. Just one comment from
Rafael (https://lkml.org/lkml/2014/8/26/780), which - as I outlined in my
response, does not apply, IMHO, since the platform does not re-enable
interrupts. Hence, I still believe fixing this in the core is the appropriate
way.

Thanks,
Sören

Changes since RFC:
- remove resume notification from syscore_resume path.
---
kernel/power/hibernate.c | 9 +++++++++
kernel/power/suspend.c | 5 +++++
kernel/time/timekeeping.c | 3 ---
3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index a9dfa79b6bab..76f15644aec8 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -285,6 +285,8 @@ static int create_image(int platform_mode)
if (error || hibernation_test(TEST_CPUS))
goto Enable_cpus;

+ clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
+
local_irq_disable();

error = syscore_suspend();
@@ -316,6 +318,7 @@ static int create_image(int platform_mode)
syscore_resume();

Enable_irqs:
+ clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
local_irq_enable();

Enable_cpus:
@@ -438,6 +441,8 @@ static int resume_target_kernel(bool platform_mode)
if (error)
goto Enable_cpus;

+ clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
+
local_irq_disable();

error = syscore_suspend();
@@ -472,6 +477,7 @@ static int resume_target_kernel(bool platform_mode)
syscore_resume();

Enable_irqs:
+ clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
local_irq_enable();

Enable_cpus:
@@ -550,6 +556,8 @@ int hibernation_platform_enter(void)
if (error)
goto Platform_finish;

+ clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
+
local_irq_disable();
syscore_suspend();
if (pm_wakeup_pending()) {
@@ -563,6 +571,7 @@ int hibernation_platform_enter(void)

Power_up:
syscore_resume();
+ clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
local_irq_enable();
enable_nonboot_cpus();

diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 18c62195660f..ded3c7d6731f 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -12,6 +12,7 @@
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/init.h>
+#include <linux/clockchips.h>
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/cpuidle.h>
@@ -294,6 +295,8 @@ static int suspend_enter(suspend_state_t state, bool *wakeup)
if (error || suspend_test(TEST_CPUS))
goto Enable_cpus;

+ clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
+
arch_suspend_disable_irqs();
BUG_ON(!irqs_disabled());

@@ -311,6 +314,8 @@ static int suspend_enter(suspend_state_t state, bool *wakeup)
syscore_resume();
}

+ clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
+
arch_suspend_enable_irqs();
BUG_ON(irqs_disabled());

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index ec1791fae965..5b6696772ffc 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1189,8 +1189,6 @@ static void timekeeping_resume(void)

touch_softlockup_watchdog();

- clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
-
/* Resume hrtimers */
hrtimers_resume();
}
@@ -1243,7 +1241,6 @@ static int timekeeping_suspend(void)
write_seqcount_end(&tk_core.seq);
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);

- clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
clocksource_suspend();
clockevents_suspend();

--
2.1.0.1.g27b9230
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2014-09-22 19:41    [W:0.064 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site