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Commit ecdcc023 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[S390] Switch etr from tasklet to workqueue. 



The clock synchronization of the ETR code requires an smp_call_function
to synchronize all cpus. Calling smp_call_function from a tasklet is
illegal. Replace the tasklet with a job on the global workqueue.
ETR work is rare and can be postponed to a be done by a kernel thread.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 6c210482

arch/s390/kernel/time.c

+17 −17
Original line number Diff line number Diff line
@@ -280,7 +280,6 @@ static void clock_comparator_interrupt(__u16 code) 
}



static void etr_reset(void);

static void etr_init(void);

static void etr_ext_handler(__u16);



/*
@@ -355,7 +354,6 @@ void __init time_init(void) 
#ifdef CONFIG_VIRT_TIMER

	vtime_init();

#endif

	etr_init();

}



/*
@@ -426,11 +424,11 @@ static struct etr_aib etr_port1; 
static int etr_port1_uptodate;

static unsigned long etr_events;

static struct timer_list etr_timer;

static struct tasklet_struct etr_tasklet;

static DEFINE_PER_CPU(atomic_t, etr_sync_word);



static void etr_timeout(unsigned long dummy);

static void etr_tasklet_fn(unsigned long dummy);

static void etr_work_fn(struct work_struct *work);

static DECLARE_WORK(etr_work, etr_work_fn);



/*

 * The etr get_clock function. It will write the current clock value
@@ -507,29 +505,31 @@ static void etr_reset(void) 
	}

}



static void etr_init(void)

static int __init etr_init(void)

{

	struct etr_aib aib;



	if (test_bit(ETR_FLAG_ENOSYS, &etr_flags))

		return;

		return 0;

	/* Check if this machine has the steai instruction. */

	if (etr_steai(&aib, ETR_STEAI_STEPPING_PORT) == 0)

		set_bit(ETR_FLAG_STEAI, &etr_flags);

	setup_timer(&etr_timer, etr_timeout, 0UL);

	tasklet_init(&etr_tasklet, etr_tasklet_fn, 0);

	if (!etr_port0_online && !etr_port1_online)

		set_bit(ETR_FLAG_EACCES, &etr_flags);

	if (etr_port0_online) {

		set_bit(ETR_EVENT_PORT0_CHANGE, &etr_events);

		tasklet_hi_schedule(&etr_tasklet);

		schedule_work(&etr_work);

	}

	if (etr_port1_online) {

		set_bit(ETR_EVENT_PORT1_CHANGE, &etr_events);

		tasklet_hi_schedule(&etr_tasklet);

		schedule_work(&etr_work);

	}

	return 0;

}



arch_initcall(etr_init);



/*

 * Two sorts of ETR machine checks. The architecture reads:

 * "When a machine-check niterruption occurs and if a switch-to-local or
@@ -549,7 +549,7 @@ void etr_switch_to_local(void) 
		return;

	etr_disable_sync_clock(NULL);

	set_bit(ETR_EVENT_SWITCH_LOCAL, &etr_events);

	tasklet_hi_schedule(&etr_tasklet);

	schedule_work(&etr_work);

}



/*
@@ -564,7 +564,7 @@ void etr_sync_check(void) 
		return;

	etr_disable_sync_clock(NULL);

	set_bit(ETR_EVENT_SYNC_CHECK, &etr_events);

	tasklet_hi_schedule(&etr_tasklet);

	schedule_work(&etr_work);

}



/*
@@ -591,13 +591,13 @@ static void etr_ext_handler(__u16 code) 
		 * Both ports are not up-to-date now.

		 */

		set_bit(ETR_EVENT_PORT_ALERT, &etr_events);

	tasklet_hi_schedule(&etr_tasklet);

	schedule_work(&etr_work);

}



static void etr_timeout(unsigned long dummy)

{

	set_bit(ETR_EVENT_UPDATE, &etr_events);

	tasklet_hi_schedule(&etr_tasklet);

	schedule_work(&etr_work);

}



/*
@@ -927,7 +927,7 @@ static struct etr_eacr etr_handle_update(struct etr_aib *aib, 
	if (!eacr.e0 && !eacr.e1)

		return eacr;



	/* Update port0 or port1 with aib stored in etr_tasklet_fn. */

	/* Update port0 or port1 with aib stored in etr_work_fn. */

	if (aib->esw.q == 0) {

		/* Information for port 0 stored. */

		if (eacr.p0 && !etr_port0_uptodate) {
@@ -1007,7 +1007,7 @@ static void etr_update_eacr(struct etr_eacr eacr) 
 * particular this is the only function that calls etr_update_eacr(),

 * it "controls" the etr control register.

 */

static void etr_tasklet_fn(unsigned long dummy)

static void etr_work_fn(struct work_struct *work)

{

	unsigned long long now;

	struct etr_eacr eacr;
@@ -1220,13 +1220,13 @@ static ssize_t etr_online_store(struct sys_device *dev, 
			return count;	/* Nothing to do. */

		etr_port0_online = value;

		set_bit(ETR_EVENT_PORT0_CHANGE, &etr_events);

		tasklet_hi_schedule(&etr_tasklet);

		schedule_work(&etr_work);

	} else {

		if (etr_port1_online == value)

			return count;	/* Nothing to do. */

		etr_port1_online = value;

		set_bit(ETR_EVENT_PORT1_CHANGE, &etr_events);

		tasklet_hi_schedule(&etr_tasklet);

		schedule_work(&etr_work);

	}

	return count;

}