* [PATCH 0/2][RFC v6] Ignore bogus sleep time if pm_trace is enabled
@ 2016-11-08 9:00 Chen Yu
2016-11-08 9:01 ` [PATCH 1/2][RFC v6] timekeeping: Ignore the " Chen Yu
2016-11-08 9:02 ` [PATCH 2/2][RFC v6] PM / sleep: save/restore RTC time after resumed if pm_trace enabled Chen Yu
0 siblings, 2 replies; 5+ messages in thread
From: Chen Yu @ 2016-11-08 9:00 UTC (permalink / raw)
To: x86
Cc: Thomas Gleixner, Rafael J. Wysocki, Len Brown, John Stultz,
Xunlei Pang, linux-pm, rtc-linux, linux-kernel, Chen Yu
This patch set is based on Thomas's previous solution, to bypass
the bogus CMOS-RTC sleep time after resumed, thus to avoid damage
to timekeeping system. The bogus sleep time comes from pm_trace,
which might use CMOS-RTC for debugging purpose.
Meanwhile, a solution to save/restore of CMOS-RTC is also proposed to give
better user experience.
Chen Yu (2):
timekeeping: Ignore the bogus sleep time if pm_trace is enabled
PM / sleep: save/restore RTC time after resumed if pm_trace enabled
arch/x86/kernel/rtc.c | 9 +++++++++
drivers/base/power/trace.c | 31 +++++++++++++++++++++++++++++++
drivers/rtc/rtc-cmos.c | 7 +++++++
include/linux/mc146818rtc.h | 1 +
include/linux/pm-trace.h | 9 ++++++++-
5 files changed, 56 insertions(+), 1 deletion(-)
--
2.7.4
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH 1/2][RFC v6] timekeeping: Ignore the bogus sleep time if pm_trace is enabled
2016-11-08 9:00 [PATCH 0/2][RFC v6] Ignore bogus sleep time if pm_trace is enabled Chen Yu
@ 2016-11-08 9:01 ` Chen Yu
2016-11-08 12:50 ` Chen Yu
2016-11-08 9:02 ` [PATCH 2/2][RFC v6] PM / sleep: save/restore RTC time after resumed if pm_trace enabled Chen Yu
1 sibling, 1 reply; 5+ messages in thread
From: Chen Yu @ 2016-11-08 9:01 UTC (permalink / raw)
To: x86
Cc: Pavel Machek, Ingo Molnar, H. Peter Anvin, linux-pm, rtc-linux,
linux-kernel, Thomas Gleixner, Rafael J. Wysocki, Len Brown,
John Stultz, Xunlei Pang, Chen Yu
From: Thomas Gleixner <tglx@linutronix.de>
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 to bypass the bogus rtc interval when pm_trace is enabled.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/rtc.c | 9 +++++++++
drivers/base/power/trace.c | 2 ++
drivers/rtc/rtc-cmos.c | 7 +++++++
include/linux/mc146818rtc.h | 1 +
include/linux/pm-trace.h | 9 ++++++++-
5 files changed, 27 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..aa9109a 100644
--- a/drivers/base/power/trace.c
+++ b/drivers/base/power/trace.c
@@ -74,6 +74,7 @@
#define DEVSEED (7919)
+bool pm_trace_rtc_abused __read_mostly;
static unsigned int dev_hash_value;
static int set_magic_time(unsigned int user, unsigned int file, unsigned int device)
@@ -104,6 +105,7 @@ 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;
}
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
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH 2/2][RFC v6] PM / sleep: save/restore RTC time after resumed if pm_trace enabled
2016-11-08 9:00 [PATCH 0/2][RFC v6] Ignore bogus sleep time if pm_trace is enabled Chen Yu
2016-11-08 9:01 ` [PATCH 1/2][RFC v6] timekeeping: Ignore the " Chen Yu
@ 2016-11-08 9:02 ` Chen Yu
2016-11-08 12:43 ` Chen Yu
1 sibling, 1 reply; 5+ messages in thread
From: Chen Yu @ 2016-11-08 9:02 UTC (permalink / raw)
To: x86
Cc: Pavel Machek, linux-pm, linux-kernel, Chen Yu, Rafael J. Wysocki,
Thomas Gleixner, Len Brown, John Stultz, Xunlei Pang
Previously the bogus CMOS RTC sleep time has been ignored if pm_trace
is enabled, however once the system successfully resumed back,
any further read to CMOS RTC would return an error. Actually it is
more user-friendly to bring the system back to normal after resumed.
This patch has registered an pm notifier to restore the RTC to the
value before been overwitten by pm_trace.
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Len Brown <lenb@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
drivers/base/power/trace.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c
index aa9109a..1e6c611 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>
@@ -76,6 +77,11 @@
bool pm_trace_rtc_abused __read_mostly;
static unsigned int dev_hash_value;
+struct rtc_time_save {
+ struct rtc_time time;
+ atomic_t saved;
+};
+static struct rtc_time_save rtc_saved;
static int set_magic_time(unsigned int user, unsigned int file, unsigned int device)
{
@@ -104,6 +110,8 @@ static int set_magic_time(unsigned int user, unsigned int file, unsigned int dev
n /= 24;
time.tm_min = (n % 20) * 3;
n /= 20;
+ if (!atomic_cmpxchg(&rtc_saved.saved, 0, 1))
+ mc146818_get_time(&rtc_saved.time);
mc146818_set_time(&time);
pm_trace_rtc_abused = true;
return n ? -1 : 0;
@@ -240,10 +248,31 @@ 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 (atomic_cmpxchg(&rtc_saved.saved, 1, 0)) {
+ mc146818_set_time(&rtc_saved.time);
+ pm_trace_rtc_abused = false;
+ }
+ 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;
}
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2][RFC v6] PM / sleep: save/restore RTC time after resumed if pm_trace enabled
2016-11-08 9:02 ` [PATCH 2/2][RFC v6] PM / sleep: save/restore RTC time after resumed if pm_trace enabled Chen Yu
@ 2016-11-08 12:43 ` Chen Yu
0 siblings, 0 replies; 5+ messages in thread
From: Chen Yu @ 2016-11-08 12:43 UTC (permalink / raw)
To: x86
Cc: Pavel Machek, linux-pm, linux-kernel, Rafael J. Wysocki,
Thomas Gleixner, Len Brown, John Stultz, Xunlei Pang
Hi all,
On Tue, Nov 08, 2016 at 05:02:14PM +0800, Chen Yu wrote:
> Previously the bogus CMOS RTC sleep time has been ignored if pm_trace
> is enabled, however once the system successfully resumed back,
> any further read to CMOS RTC would return an error. Actually it is
> more user-friendly to bring the system back to normal after resumed.
>
> This patch has registered an pm notifier to restore the RTC to the
> value before been overwitten by pm_trace.
>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Len Brown <lenb@kernel.org>
> Cc: John Stultz <john.stultz@linaro.org>
> Cc: Xunlei Pang <xlpang@redhat.com>
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> ---
Please ignore this version for now,
the atomic variable below is unnecessary since
pm_trace has disabled the async suspend.
And in order to allow the users to adjust rtc after resume,
we can clear the pm_trace_rtc_abused directly and warn users of
the broken rtc. (Without save/restore).
> drivers/base/power/trace.c | 29 +++++++++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c
> index aa9109a..1e6c611 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>
>
> @@ -76,6 +77,11 @@
>
> bool pm_trace_rtc_abused __read_mostly;
> static unsigned int dev_hash_value;
> +struct rtc_time_save {
> + struct rtc_time time;
> + atomic_t saved;
> +};
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 1/2][RFC v6] timekeeping: Ignore the bogus sleep time if pm_trace is enabled
2016-11-08 9:01 ` [PATCH 1/2][RFC v6] timekeeping: Ignore the " Chen Yu
@ 2016-11-08 12:50 ` Chen Yu
0 siblings, 0 replies; 5+ messages in thread
From: Chen Yu @ 2016-11-08 12:50 UTC (permalink / raw)
To: x86
Cc: Pavel Machek, Ingo Molnar, H. Peter Anvin, linux-pm, rtc-linux,
linux-kernel, Thomas Gleixner, Rafael J. Wysocki, Len Brown,
John Stultz, Xunlei Pang
On Tue, Nov 08, 2016 at 05:01:35PM +0800, Chen Yu wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
>
> 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 to bypass the bogus rtc interval when pm_trace is enabled.
>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Len Brown <lenb@kernel.org>
> Cc: John Stultz <john.stultz@linaro.org>
> Cc: Xunlei Pang <xlpang@redhat.com>
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> ---
>
[cut]
Will resend another version. Thanks.
^ permalink raw reply [flat|nested] 5+ messages in thread
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