* [rtc-linux] [PATCH 1/2][RFC v6] timekeeping: Ignore the bogus sleep time if pm_trace is enabled
2016-11-08 9:00 [rtc-linux] [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 ` [rtc-linux] " Chen Yu
0 siblings, 1 reply; 3+ 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
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