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Message-ID: <4695836.GXAFRqVoOG@kreacher>
Date: Fri, 04 Feb 2022 18:35:22 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux ACPI <linux-acpi@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Linux PM <linux-pm@...r.kernel.org>,
Zhang Rui <rui.zhang@...el.com>,
David Box <david.e.box@...ux.intel.com>
Subject: [PATCH v1 2/2] PM: s2idle: ACPI: Fix wakeup interrupts handling
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
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@...r.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
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);
}
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