diff options
| -rw-r--r-- | include/linux/tick.h | 3 | ||||
| -rw-r--r-- | kernel/time/clocksource.c | 20 | ||||
| -rw-r--r-- | kernel/time/tick-oneshot.c | 17 |
3 files changed, 39 insertions, 1 deletions
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 diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 80189f6f1c5a..592bf584d1d2 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -509,6 +509,18 @@ static ssize_t sysfs_override_clocksource(struct sys_device *dev, } } + /* + * Check to make sure we don't switch to a non-highres capable + * clocksource if the tick code is in oneshot mode (highres or nohz) + */ + if (tick_oneshot_mode_active() && + !(ovr->flags & CLOCK_SOURCE_VALID_FOR_HRES)) { + printk(KERN_WARNING "%s clocksource is not HRT compatible. " + "Cannot switch while in HRT/NOHZ mode\n", ovr->name); + ovr = NULL; + override_name[0] = 0; + } + /* Reselect, when the override name has changed */ if (ovr != clocksource_override) { clocksource_override = ovr; @@ -537,7 +549,13 @@ sysfs_show_available_clocksources(struct sys_device *dev, spin_lock_irq(&clocksource_lock); list_for_each_entry(src, &clocksource_list, list) { - count += snprintf(buf + count, + /* + * Don't show non-HRES clocksource if the tick code is + * in one shot mode (highres=on or nohz=on) + */ + if (!tick_oneshot_mode_active() || + (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) + count += snprintf(buf + count, max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "%s ", src->name); } diff --git a/kernel/time/tick-oneshot.c b/kernel/time/tick-oneshot.c index 2e8de678e767..a96c0e2b89cf 100644 --- a/kernel/time/tick-oneshot.c +++ b/kernel/time/tick-oneshot.c @@ -128,6 +128,23 @@ int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *)) return 0; } +/** + * tick_check_oneshot_mode - check whether the system is in oneshot mode + * + * returns 1 when either nohz or highres are enabled. otherwise 0. + */ +int tick_oneshot_mode_active(void) +{ + unsigned long flags; + int ret; + + local_irq_save(flags); + ret = __get_cpu_var(tick_cpu_device).mode == TICKDEV_MODE_ONESHOT; + local_irq_restore(flags); + + return ret; +} + #ifdef CONFIG_HIGH_RES_TIMERS /** * tick_init_highres - switch to high resolution mode |