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authorLinus Torvalds <torvalds@linux-foundation.org>2009-06-15 12:58:33 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-15 12:58:33 -0400
commit3f27c0d2a469673e0f1efc8004b6f42428aa5b94 (patch)
tree548c975cabdcafcac92992d24410ae0a8334dff5
parent9aaa630503f20461bee65ebc4fd87ba8d7a2bd2c (diff)
parentcd6d95d8449b7c9f415f26041e9ae173d387b6bd (diff)
Merge branch 'timers-for-linus-clocksource' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-for-linus-clocksource' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: clocksource: prevent selection of low resolution clocksourse also for nohz=on clocksource: sanity check sysfs clocksource changes
-rw-r--r--include/linux/tick.h3
-rw-r--r--kernel/time/clocksource.c20
-rw-r--r--kernel/time/tick-oneshot.c17
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);
97extern int tick_check_oneshot_change(int allow_nohz); 97extern int tick_check_oneshot_change(int allow_nohz);
98extern struct tick_sched *tick_get_tick_sched(int cpu); 98extern struct tick_sched *tick_get_tick_sched(int cpu);
99extern void tick_check_idle(int cpu); 99extern void tick_check_idle(int cpu);
100extern int tick_oneshot_mode_active(void);
100# else 101# else
101static inline void tick_clock_notify(void) { } 102static inline void tick_clock_notify(void) { }
102static inline int tick_check_oneshot_change(int allow_nohz) { return 0; } 103static inline int tick_check_oneshot_change(int allow_nohz) { return 0; }
103static inline void tick_check_idle(int cpu) { } 104static inline void tick_check_idle(int cpu) { }
105static inline int tick_oneshot_mode_active(void) { return 0; }
104# endif 106# endif
105 107
106#else /* CONFIG_GENERIC_CLOCKEVENTS */ 108#else /* CONFIG_GENERIC_CLOCKEVENTS */
@@ -109,6 +111,7 @@ static inline void tick_cancel_sched_timer(int cpu) { }
109static inline void tick_clock_notify(void) { } 111static inline void tick_clock_notify(void) { }
110static inline int tick_check_oneshot_change(int allow_nohz) { return 0; } 112static inline int tick_check_oneshot_change(int allow_nohz) { return 0; }
111static inline void tick_check_idle(int cpu) { } 113static inline void tick_check_idle(int cpu) { }
114static inline int tick_oneshot_mode_active(void) { return 0; }
112#endif /* !CONFIG_GENERIC_CLOCKEVENTS */ 115#endif /* !CONFIG_GENERIC_CLOCKEVENTS */
113 116
114# ifdef CONFIG_NO_HZ 117# 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,
509 } 509 }
510 } 510 }
511 511
512 /*
513 * Check to make sure we don't switch to a non-highres capable
514 * clocksource if the tick code is in oneshot mode (highres or nohz)
515 */
516 if (tick_oneshot_mode_active() &&
517 !(ovr->flags & CLOCK_SOURCE_VALID_FOR_HRES)) {
518 printk(KERN_WARNING "%s clocksource is not HRT compatible. "
519 "Cannot switch while in HRT/NOHZ mode\n", ovr->name);
520 ovr = NULL;
521 override_name[0] = 0;
522 }
523
512 /* Reselect, when the override name has changed */ 524 /* Reselect, when the override name has changed */
513 if (ovr != clocksource_override) { 525 if (ovr != clocksource_override) {
514 clocksource_override = ovr; 526 clocksource_override = ovr;
@@ -537,7 +549,13 @@ sysfs_show_available_clocksources(struct sys_device *dev,
537 549
538 spin_lock_irq(&clocksource_lock); 550 spin_lock_irq(&clocksource_lock);
539 list_for_each_entry(src, &clocksource_list, list) { 551 list_for_each_entry(src, &clocksource_list, list) {
540 count += snprintf(buf + count, 552 /*
553 * Don't show non-HRES clocksource if the tick code is
554 * in one shot mode (highres=on or nohz=on)
555 */
556 if (!tick_oneshot_mode_active() ||
557 (src->flags & CLOCK_SOURCE_VALID_FOR_HRES))
558 count += snprintf(buf + count,
541 max((ssize_t)PAGE_SIZE - count, (ssize_t)0), 559 max((ssize_t)PAGE_SIZE - count, (ssize_t)0),
542 "%s ", src->name); 560 "%s ", src->name);
543 } 561 }
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 *))
128 return 0; 128 return 0;
129} 129}
130 130
131/**
132 * tick_check_oneshot_mode - check whether the system is in oneshot mode
133 *
134 * returns 1 when either nohz or highres are enabled. otherwise 0.
135 */
136int tick_oneshot_mode_active(void)
137{
138 unsigned long flags;
139 int ret;
140
141 local_irq_save(flags);
142 ret = __get_cpu_var(tick_cpu_device).mode == TICKDEV_MODE_ONESHOT;
143 local_irq_restore(flags);
144
145 return ret;
146}
147
131#ifdef CONFIG_HIGH_RES_TIMERS 148#ifdef CONFIG_HIGH_RES_TIMERS
132/** 149/**
133 * tick_init_highres - switch to high resolution mode 150 * tick_init_highres - switch to high resolution mode