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Commit 3c4fbe5e authored by Miao Xie's avatar Miao Xie Committed by Ingo Molnar
Browse files

nohz: fix wrong event handler after online an offlined cpu 



On the tickless system(CONFIG_NO_HZ=y and CONFIG_HIGH_RES_TIMERS=n), after
I made an offlined cpu online, I found this cpu's event handler was
tick_handle_periodic, not tick_nohz_handler.

After debuging, I found this bug was caused by the wrong tick mode.  the
tick mode is not changed to NOHZ_MODE_INACTIVE when the cpu is offline.

This patch fixes this bug.

Signed-off-by: default avatarMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 6a55617e

include/linux/tick.h

+4 −1
Original line number Diff line number Diff line
@@ -74,10 +74,13 @@ extern struct tick_device *tick_get_device(int cpu); 
extern int tick_init_highres(void);

extern int tick_program_event(ktime_t expires, int force);

extern void tick_setup_sched_timer(void);

# endif



# if defined CONFIG_NO_HZ || defined CONFIG_HIGH_RES_TIMERS

extern void tick_cancel_sched_timer(int cpu);

# else

static inline void tick_cancel_sched_timer(int cpu) { }

# endif /* HIGHRES */

# endif



# ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST

extern struct tick_device *tick_get_broadcast_device(void);

kernel/time/tick-sched.c

+5 −1
Original line number Diff line number Diff line
@@ -643,17 +643,21 @@ void tick_setup_sched_timer(void) 
		ts->nohz_mode = NOHZ_MODE_HIGHRES;

#endif

}

#endif /* HIGH_RES_TIMERS */



#if defined CONFIG_NO_HZ || defined CONFIG_HIGH_RES_TIMERS

void tick_cancel_sched_timer(int cpu)

{

	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);



# ifdef CONFIG_HIGH_RES_TIMERS

	if (ts->sched_timer.base)

		hrtimer_cancel(&ts->sched_timer);

# endif



	ts->nohz_mode = NOHZ_MODE_INACTIVE;

}

#endif /* HIGH_RES_TIMERS */

#endif



/**

 * Async notification about clocksource changes