[PATCH 5.10 048/116] PM: s2idle: ACPI: Fix wakeup interrupts handling

Greg Kroah-Hartman
2022-02-14T09:52:05Z

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

commit cb1f65c1e1424a4b5e4a86da8aa3b8fd8459c8ec upstream.

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+ <stable@vger.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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(-)

--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -1040,6 +1040,7 @@ static bool acpi_s2idle_wake(void)
return true;
}

+ pm_wakeup_clear(acpi_sci_irq);
rearm_wake_irq(acpi_sci_irq);
}

--- a/drivers/base/power/wakeup.c
+++ b/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;
@@ -941,19 +942,45 @@ 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];
}

/**
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -496,14 +496,14 @@ 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);
--- a/kernel/power/main.c
+++ b/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);
--- a/kernel/power/process.c
+++ b/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);
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -138,8 +138,6 @@ static void s2idle_loop(void)
break;
}

- pm_wakeup_clear(false);
-
s2idle_enter();
}