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Commit 4b7e0706 authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Linus Torvalds
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[PATCH] s390: idle timer setup 



Fix overflow in calculation of the new tod value in stop_hz_timer and fix
wrong virtual timer list idle time in case the virtual timer is already
expired in stop_cpu_timer.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent b2c6678c

arch/s390/kernel/time.c

+9 −3
Original line number Original line Diff line number Diff line
@@ -244,7 +244,7 @@ int sysctl_hz_timer = 1; 
 */

 */

static inline void stop_hz_timer(void)

static inline void stop_hz_timer(void)

{

{

	__u64 timer;

	__u64 timer, todval;





	if (sysctl_hz_timer != 0)

	if (sysctl_hz_timer != 0)

		return;

		return;
@@ -265,8 +265,14 @@ static inline void stop_hz_timer(void) 
	 * for the next event.

	 * for the next event.

	 */

	 */

	timer = (__u64) (next_timer_interrupt() - jiffies) + jiffies_64;

	timer = (__u64) (next_timer_interrupt() - jiffies) + jiffies_64;

	todval = -1ULL;

	/* Be careful about overflows. */

	if (timer < (-1ULL / CLK_TICKS_PER_JIFFY)) {

		timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY;

		timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY;

	asm volatile ("SCKC %0" : : "m" (timer));

		if (timer >= jiffies_timer_cc)

			todval = timer;

	}

	asm volatile ("SCKC %0" : : "m" (todval));

}

}





/*

/*

arch/s390/kernel/vtime.c

+13 −12
Original line number Original line Diff line number Diff line
@@ -122,12 +122,17 @@ static void start_cpu_timer(void) 
	struct vtimer_queue *vt_list;

	struct vtimer_queue *vt_list;





	vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());

	vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());



	/* CPU timer interrupt is pending, don't reprogramm it */

	if (vt_list->idle & 1LL<<63)

		return;



	if (!list_empty(&vt_list->list))

		set_vtimer(vt_list->idle);

		set_vtimer(vt_list->idle);

}

}





static void stop_cpu_timer(void)

static void stop_cpu_timer(void)

{

{

	__u64 done;

	struct vtimer_queue *vt_list;

	struct vtimer_queue *vt_list;





	vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());

	vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());
@@ -138,21 +143,17 @@ static void stop_cpu_timer(void) 
		goto fire;

		goto fire;

	}

	}





	/* store progress */

	/* store the actual expire value */

	asm volatile ("STPT %0" : "=m" (done));

	asm volatile ("STPT %0" : "=m" (vt_list->idle));





	/*

	/*

	 * If done is negative we do not stop the CPU timer

	 * If the CPU timer is negative we don't reprogramm

	 * because we will get instantly an interrupt that

	 * it because we will get instantly an interrupt.

	 * will start the CPU timer again.

	 */

	 */

	if (done & 1LL<<63)

	if (vt_list->idle & 1LL<<63)

		return;

		return;

	else

		vt_list->offset += vt_list->to_expire - done;





	/* save the actual expire value */

	vt_list->offset += vt_list->to_expire - vt_list->idle;

	vt_list->idle = done;





	/*

	/*

	 * We cannot halt the CPU timer, we just write a value that

	 * We cannot halt the CPU timer, we just write a value that