From 3f68535adad8dd89499505a65fb25d0e02d118cc Mon Sep 17 00:00:00 2001 From: john stultz Date: Wed, 21 Jan 2009 22:53:22 -0700 Subject: clocksource: sanity check sysfs clocksource changes Thomas, Andrew and Ingo pointed out that we don't have any safety checks in the clocksource sysfs entries to make sure sysadmins don't try to change the clocksource to a non high-res timer capable clocksource (such as jiffies) when high-res timers (HRT) is enabled. Doing so will likely hang a system. Correct this by filtering non HRT clocksources from available_clocksources and not accepting non HRT clocksources with HRT enabled. Signed-off-by: John Stultz Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- include/linux/hrtimer.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 0d2f7c8a33d6..58021b0c396d 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -305,7 +305,7 @@ static inline int hrtimer_is_hres_active(struct hrtimer *timer) extern ktime_t ktime_get(void); extern ktime_t ktime_get_real(void); - +extern int hrtimer_hres_active(void); DECLARE_PER_CPU(struct tick_device, tick_cpu_device); -- cgit v1.2.2 From cd6d95d8449b7c9f415f26041e9ae173d387b6bd Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 12 Jun 2009 11:29:27 +0200 Subject: clocksource: prevent selection of low resolution clocksourse also for nohz=on commit 3f68535adad (clocksource: sanity check sysfs clocksource changes) prevents selection of non high resolution capable clocksources when high resolution mode is active, but did not take into account that the same rules apply for highres=off nohz=on. Check the tick device mode instead of hrtimer_hres_active() to verify whether the system needs to be protected from a switch to jiffies or other non highres capable clock sources. Reported-by: Luming Yu Signed-off-by: Thomas Gleixner --- include/linux/hrtimer.h | 2 +- include/linux/tick.h | 3 +++ 2 files changed, 4 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 58021b0c396d..0d2f7c8a33d6 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -305,7 +305,7 @@ static inline int hrtimer_is_hres_active(struct hrtimer *timer) extern ktime_t ktime_get(void); extern ktime_t ktime_get_real(void); -extern int hrtimer_hres_active(void); + DECLARE_PER_CPU(struct tick_device, tick_cpu_device); diff --git a/include/linux/tick.h b/include/linux/tick.h index 469b82d88b3b..0482229c07db 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -97,10 +97,12 @@ extern void tick_clock_notify(void); extern int tick_check_oneshot_change(int allow_nohz); extern struct tick_sched *tick_get_tick_sched(int cpu); extern void tick_check_idle(int cpu); +extern int tick_oneshot_mode_active(void); # else static inline void tick_clock_notify(void) { } static inline int tick_check_oneshot_change(int allow_nohz) { return 0; } static inline void tick_check_idle(int cpu) { } +static inline int tick_oneshot_mode_active(void) { return 0; } # endif #else /* CONFIG_GENERIC_CLOCKEVENTS */ @@ -109,6 +111,7 @@ static inline void tick_cancel_sched_timer(int cpu) { } static inline void tick_clock_notify(void) { } static inline int tick_check_oneshot_change(int allow_nohz) { return 0; } static inline void tick_check_idle(int cpu) { } +static inline int tick_oneshot_mode_active(void) { return 0; } #endif /* !CONFIG_GENERIC_CLOCKEVENTS */ # ifdef CONFIG_NO_HZ -- cgit v1.2.2