From: Thomas Gleixner <[email protected]> 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 <[email protected]> Cc: "Rafael J. Wysocki" <[email protected]> Cc: Len Brown <[email protected]> Cc: John Stultz <[email protected]> Cc: Xunlei Pang <[email protected]> Signed-off-by: Chen Yu <[email protected]> --- 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
