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Groups > linux.kernel > #1525854
| From | John Stultz <john.stultz@linaro.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 3/4] timekeeping: Ignore the bogus sleep time if pm_trace is enabled |
| Date | 2016-11-19 06:00 +0100 |
| Message-ID | <sF5UR-78-5@gated-at.bofh.it> (permalink) |
| References | <sF5UR-78-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: Chen Yu <yu.c.chen@intel.com>
Previously we encountered some memory overflow issues due to
the bogus sleep time brought by inconsistent rtc, which is
triggered when pm_trace is enabled, and we have fixed it
in recent kernel. However it's improper in the first place
to call __timekeeping_inject_sleeptime() in case that pm_trace
is enabled simply because that "hash" time value will wreckage
the timekeeping subsystem.
This patch is originally written by Thomas, which would bypass
the bogus rtc interval when pm_trace is enabled.
Meanwhile, if system succeed to resume back with pm_trace set, the
users are warned to adjust the bogus rtc either by ntp-date or rdate,
by resetting pm_trace_rtc_abused to false, otherwise above tools might
not work as expected.
Originally-from: Thomas Gleixner <tglx@linutronix.de>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Xunlei Pang <xlpang@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Len Brown <lenb@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
arch/x86/kernel/rtc.c | 9 +++++++++
drivers/base/power/trace.c | 27 +++++++++++++++++++++++++++
drivers/rtc/rtc-cmos.c | 7 +++++++
include/linux/mc146818rtc.h | 1 +
include/linux/pm-trace.h | 9 ++++++++-
5 files changed, 52 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index 79c6311c..898383c 100644
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -64,6 +64,15 @@ void mach_get_cmos_time(struct timespec *now)
unsigned int status, year, mon, day, hour, min, sec, century = 0;
unsigned long flags;
+ /*
+ * If pm trace abused the RTC as storage set the timespec to 0
+ * which tells the caller that this RTC value is bogus.
+ */
+ if (!pm_trace_rtc_valid()) {
+ now->tv_sec = now->tv_nsec = 0;
+ return;
+ }
+
spin_lock_irqsave(&rtc_lock, flags);
/*
diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c
index efec10b..209e214 100644
--- a/drivers/base/power/trace.c
+++ b/drivers/base/power/trace.c
@@ -10,6 +10,7 @@
#include <linux/pm-trace.h>
#include <linux/export.h>
#include <linux/rtc.h>
+#include <linux/suspend.h>
#include <linux/mc146818rtc.h>
@@ -74,6 +75,9 @@
#define DEVSEED (7919)
+bool pm_trace_rtc_abused __read_mostly;
+EXPORT_SYMBOL(pm_trace_rtc_abused);
+
static unsigned int dev_hash_value;
static int set_magic_time(unsigned int user, unsigned int file, unsigned int device)
@@ -104,6 +108,7 @@ static int set_magic_time(unsigned int user, unsigned int file, unsigned int dev
time.tm_min = (n % 20) * 3;
n /= 20;
mc146818_set_time(&time);
+ pm_trace_rtc_abused = true;
return n ? -1 : 0;
}
@@ -238,10 +243,32 @@ int show_trace_dev_match(char *buf, size_t size)
device_pm_unlock();
return ret;
}
+static int pm_trace_notify(struct notifier_block *nb,
+ unsigned long mode, void *_unused)
+{
+ switch (mode) {
+ case PM_POST_HIBERNATION:
+ case PM_POST_SUSPEND:
+ if (pm_trace_rtc_abused) {
+ pm_trace_rtc_abused = false;
+ pr_warn("Possible incorrect RTC due to pm_trace,"
+ "please use ntp-date or rdate to reset.\n");
+ }
+ break;
+ default:
+ break;
+ }
+ return 0;
+}
+
+static struct notifier_block pm_trace_nb = {
+ .notifier_call = pm_trace_notify,
+};
static int early_resume_init(void)
{
hash_value_early_read = read_magic_time();
+ register_pm_notifier(&pm_trace_nb);
return 0;
}
diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index dd3d598..3d9aedc 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -191,6 +191,13 @@ static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
static int cmos_read_time(struct device *dev, struct rtc_time *t)
{
+ /*
+ * If pmtrace abused the RTC for storage tell the caller that it is
+ * unusable.
+ */
+ if (!pm_trace_rtc_valid())
+ return -EIO;
+
/* REVISIT: if the clock has a "century" register, use
* that instead of the heuristic in mc146818_get_time().
* That'll make Y3K compatility (year > 2070) easy!
diff --git a/include/linux/mc146818rtc.h b/include/linux/mc146818rtc.h
index a585b4b..0661af1 100644
--- a/include/linux/mc146818rtc.h
+++ b/include/linux/mc146818rtc.h
@@ -16,6 +16,7 @@
#include <asm/mc146818rtc.h> /* register access macros */
#include <linux/bcd.h>
#include <linux/delay.h>
+#include <linux/pm-trace.h>
#ifdef __KERNEL__
#include <linux/spinlock.h> /* spinlock_t */
diff --git a/include/linux/pm-trace.h b/include/linux/pm-trace.h
index ecbde7a..7b78793 100644
--- a/include/linux/pm-trace.h
+++ b/include/linux/pm-trace.h
@@ -1,11 +1,17 @@
#ifndef PM_TRACE_H
#define PM_TRACE_H
+#include <linux/types.h>
#ifdef CONFIG_PM_TRACE
#include <asm/pm-trace.h>
-#include <linux/types.h>
extern int pm_trace_enabled;
+extern bool pm_trace_rtc_abused;
+
+static inline bool pm_trace_rtc_valid(void)
+{
+ return !pm_trace_rtc_abused;
+}
static inline int pm_trace_is_enabled(void)
{
@@ -24,6 +30,7 @@ extern int show_trace_dev_match(char *buf, size_t size);
#else
+static inline bool pm_trace_rtc_valid(void) { return true; }
static inline int pm_trace_is_enabled(void) { return 0; }
#define TRACE_DEVICE(dev) do { } while (0)
--
2.7.4
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[GIT PULL][PATCH 0/4] Timekeeping items for 4.10 John Stultz <john.stultz@linaro.org> - 2016-11-19 06:00 +0100
[PATCH 3/4] timekeeping: Ignore the bogus sleep time if pm_trace is enabled John Stultz <john.stultz@linaro.org> - 2016-11-19 06:00 +0100
Re: [PATCH 3/4] timekeeping: Ignore the bogus sleep time if pm_trace is enabled Ingo Molnar <mingo@kernel.org> - 2016-11-21 09:20 +0100
RE: [PATCH 3/4] timekeeping: Ignore the bogus sleep time if pm_trace is enabled "Chen, Yu C" <yu.c.chen@intel.com> - 2016-11-24 11:00 +0100
[PATCH 1/4] time: alarmtimer: Add the trcepoints for alarmtimer John Stultz <john.stultz@linaro.org> - 2016-11-19 06:00 +0100
Re: [PATCH 1/4] time: alarmtimer: Add the trcepoints for alarmtimer Ingo Molnar <mingo@kernel.org> - 2016-11-21 09:20 +0100
Re: [PATCH 1/4] time: alarmtimer: Add the trcepoints for alarmtimer Baolin Wang <baolin.wang@linaro.org> - 2016-11-21 09:50 +0100
Re: [PATCH 1/4] time: alarmtimer: Add the trcepoints for alarmtimer Thomas Gleixner <tglx@linutronix.de> - 2016-11-21 10:00 +0100
Re: [PATCH 1/4] time: alarmtimer: Add the trcepoints for alarmtimer Baolin Wang <baolin.wang@linaro.org> - 2016-11-21 10:10 +0100
[PATCH 2/4] selftests/timers: Fix spelling mistake "Asyncrhonous" -> "Asynchronous" John Stultz <john.stultz@linaro.org> - 2016-11-19 06:00 +0100
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