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.brinkm...@xilinx.com>
---
Hi,
there was a little of an dicussion on the RFC for this patch, but that
eventually ended (https://lkml.org/lkml/2014/7/21/493).
In the meantime I found one small flaw that is fixed in this patch (changelog
below).
This resolves the issues I see on my Zynq (ARM) platform and I also patched my
Laptop's (x86_64) kernel with this where it looks good as well. Though, in both
cases only suspend is used. Any testing - especially of hibernation - would
be much appreciated.
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 6dadb25cb0d8..6bba2f907bcb 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 fb4a9c2cf8d9..f13332185b07 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1188,8 +1188,6 @@ static void timekeeping_resume(void)
touch_softlockup_watchdog();
- clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
-
/* Resume hrtimers */
hrtimers_resume();
}
@@ -1242,7 +1240,6 @@ 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();
--
2.0.1.1.gfbfc394
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