Hi All,
Two problems with the handling of wakeup from suspend-to-idle on systems
using ACPI and the EC driver (x86 PCs mostly) have been recently discovered,
mainly by code inspection.
This series of two patches is intended to fix those problems. Please refer
to the patch changelogs for details.
Thanks!
From: Rafael J. Wysocki <[email protected]>
After commit e3728b50cd9b ("ACPI: PM: s2idle: Avoid possible race
related to the EC GPE") wakeup interrupts occurring immediately after
the one discarded by acpi_s2idle_wake() may be missed. Moreover, if
the SCI triggers again immediately after the rearming in
acpi_s2idle_wake(), that wakeup may be missed too.
The problem is that pm_system_irq_wakeup() only calls pm_system_wakeup()
when pm_wakeup_irq is 0, but that's not the case any more after the
interrupt causing acpi_s2idle_wake() to run until pm_wakeup_irq is
cleared by the pm_wakeup_clear() call in s2idle_loop(). However,
there may be wakeup interrupts occurring in that time frame and if
that happens, they will be missed.
To address that issue first move the clearing of pm_wakeup_irq to
the point at which it is known that the interrupt causing
acpi_s2idle_wake() to tun will be discarded, before rearming the SCI
for wakeup. Moreover, because that only reduces the size of the
time window in which the issue may manifest itself, allow
pm_system_irq_wakeup() to register two second wakeup interrupts in
a row and, when discarding the first one, replace it with the second
one. [Of course, this assumes that only one wakeup interrupt can be
discarded in one go, but currently that is the case and I am not
aware of any plans to change that.]
Fixes: e3728b50cd9b ("ACPI: PM: s2idle: Avoid possible race related to the EC GPE")
Cc: 5.4+ <[email protected]> # 5.4+
Signed-off-by: Rafael J. Wysocki <[email protected]>
---
drivers/acpi/sleep.c | 1 +
drivers/base/power/wakeup.c | 41 ++++++++++++++++++++++++++++++++++-------
include/linux/suspend.h | 4 ++--
kernel/power/main.c | 5 ++++-
kernel/power/process.c | 2 +-
kernel/power/suspend.c | 2 --
6 files changed, 42 insertions(+), 13 deletions(-)
Index: linux-pm/include/linux/suspend.h
===================================================================
--- linux-pm.orig/include/linux/suspend.h
+++ linux-pm/include/linux/suspend.h
@@ -497,14 +497,14 @@ extern void ksys_sync_helper(void);
/* drivers/base/power/wakeup.c */
extern bool events_check_enabled;
-extern unsigned int pm_wakeup_irq;
extern suspend_state_t pm_suspend_target_state;
extern bool pm_wakeup_pending(void);
extern void pm_system_wakeup(void);
extern void pm_system_cancel_wakeup(void);
-extern void pm_wakeup_clear(bool reset);
+extern void pm_wakeup_clear(unsigned int irq_number);
extern void pm_system_irq_wakeup(unsigned int irq_number);
+extern unsigned int pm_wakeup_irq(void);
extern bool pm_get_wakeup_count(unsigned int *count, bool block);
extern bool pm_save_wakeup_count(unsigned int count);
extern void pm_wakep_autosleep_enabled(bool set);
Index: linux-pm/kernel/power/process.c
===================================================================
--- linux-pm.orig/kernel/power/process.c
+++ linux-pm/kernel/power/process.c
@@ -134,7 +134,7 @@ int freeze_processes(void)
if (!pm_freezing)
atomic_inc(&system_freezing_cnt);
- pm_wakeup_clear(true);
+ pm_wakeup_clear(0);
pr_info("Freezing user space processes ... ");
pm_freezing = true;
error = try_to_freeze_tasks(true);
Index: linux-pm/kernel/power/suspend.c
===================================================================
--- linux-pm.orig/kernel/power/suspend.c
+++ linux-pm/kernel/power/suspend.c
@@ -136,8 +136,6 @@ static void s2idle_loop(void)
break;
}
- pm_wakeup_clear(false);
-
s2idle_enter();
}
Index: linux-pm/drivers/base/power/wakeup.c
===================================================================
--- linux-pm.orig/drivers/base/power/wakeup.c
+++ linux-pm/drivers/base/power/wakeup.c
@@ -34,7 +34,8 @@ suspend_state_t pm_suspend_target_state;
bool events_check_enabled __read_mostly;
/* First wakeup IRQ seen by the kernel in the last cycle. */
-unsigned int pm_wakeup_irq __read_mostly;
+static unsigned int wakeup_irq[2] __read_mostly;
+static DEFINE_RAW_SPINLOCK(wakeup_irq_lock);
/* If greater than 0 and the system is suspending, terminate the suspend. */
static atomic_t pm_abort_suspend __read_mostly;
@@ -942,19 +943,45 @@ void pm_system_cancel_wakeup(void)
atomic_dec_if_positive(&pm_abort_suspend);
}
-void pm_wakeup_clear(bool reset)
+void pm_wakeup_clear(unsigned int irq_number)
{
- pm_wakeup_irq = 0;
- if (reset)
+ raw_spin_lock_irq(&wakeup_irq_lock);
+
+ if (irq_number && wakeup_irq[0] == irq_number)
+ wakeup_irq[0] = wakeup_irq[1];
+ else
+ wakeup_irq[0] = 0;
+
+ wakeup_irq[1] = 0;
+
+ raw_spin_unlock_irq(&wakeup_irq_lock);
+
+ if (!irq_number)
atomic_set(&pm_abort_suspend, 0);
}
void pm_system_irq_wakeup(unsigned int irq_number)
{
- if (pm_wakeup_irq == 0) {
- pm_wakeup_irq = irq_number;
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&wakeup_irq_lock, flags);
+
+ if (wakeup_irq[0] == 0)
+ wakeup_irq[0] = irq_number;
+ else if (wakeup_irq[1] == 0)
+ wakeup_irq[1] = irq_number;
+ else
+ irq_number = 0;
+
+ raw_spin_unlock_irqrestore(&wakeup_irq_lock, flags);
+
+ if (irq_number)
pm_system_wakeup();
- }
+}
+
+unsigned int pm_wakeup_irq(void)
+{
+ return wakeup_irq[0];
}
/**
Index: linux-pm/kernel/power/main.c
===================================================================
--- linux-pm.orig/kernel/power/main.c
+++ linux-pm/kernel/power/main.c
@@ -504,7 +504,10 @@ static ssize_t pm_wakeup_irq_show(struct
struct kobj_attribute *attr,
char *buf)
{
- return pm_wakeup_irq ? sprintf(buf, "%u\n", pm_wakeup_irq) : -ENODATA;
+ if (!pm_wakeup_irq())
+ return -ENODATA;
+
+ return sprintf(buf, "%u\n", pm_wakeup_irq());
}
power_attr_ro(pm_wakeup_irq);
Index: linux-pm/drivers/acpi/sleep.c
===================================================================
--- linux-pm.orig/drivers/acpi/sleep.c
+++ linux-pm/drivers/acpi/sleep.c
@@ -760,6 +760,7 @@ bool acpi_s2idle_wake(void)
pm_pr_dbg("Rearming ACPI SCI for wakeup\n");
+ pm_wakeup_clear(acpi_sci_irq);
rearm_wake_irq(acpi_sci_irq);
}