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Commit 8283cb43 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[S390] clock sync mode flags 



The clock sync mode flag CLOCK_SYNC_STP is not cleared when stp
is set offline. In this case the get_sync_clock() function returns
-EACCESS and the dasd driver will block all i/o until stp is enabled
again. In addition get_sync_clock can return -EACCESS if the clock is
not in sync instead of -EAGAIN.

Rework the stp/etr online handling to fix these problems.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 56e25e97

arch/s390/kernel/time.c

+44 −27
Original line number Diff line number Diff line
@@ -331,6 +331,7 @@ static unsigned long long adjust_time(unsigned long long old, 
}



static DEFINE_PER_CPU(atomic_t, clock_sync_word);

static DEFINE_MUTEX(clock_sync_mutex);

static unsigned long clock_sync_flags;



#define CLOCK_SYNC_HAS_ETR	0
@@ -394,6 +395,20 @@ static void enable_sync_clock(void) 
	atomic_set_mask(0x80000000, sw_ptr);

}



/*

 * Function to check if the clock is in sync.

 */

static inline int check_sync_clock(void)

{

	atomic_t *sw_ptr;

	int rc;



	sw_ptr = &get_cpu_var(clock_sync_word);

	rc = (atomic_read(sw_ptr) & 0x80000000U) != 0;

	put_cpu_var(clock_sync_sync);

	return rc;

}



/* Single threaded workqueue used for etr and stp sync events */

static struct workqueue_struct *time_sync_wq;
@@ -485,6 +500,8 @@ static void etr_reset(void) 
	if (etr_setr(&etr_eacr) == 0) {

		etr_tolec = get_clock();

		set_bit(CLOCK_SYNC_HAS_ETR, &clock_sync_flags);

		if (etr_port0_online && etr_port1_online)

			set_bit(CLOCK_SYNC_ETR, &clock_sync_flags);

	} else if (etr_port0_online || etr_port1_online) {

		pr_warning("The real or virtual hardware system does "

			   "not provide an ETR interface\n");
@@ -533,7 +550,6 @@ void etr_switch_to_local(void) 
{

	if (!etr_eacr.sl)

		return;

	if (test_bit(CLOCK_SYNC_ETR, &clock_sync_flags))

	disable_sync_clock(NULL);

	set_bit(ETR_EVENT_SWITCH_LOCAL, &etr_events);

	queue_work(time_sync_wq, &etr_work);
@@ -549,7 +565,6 @@ void etr_sync_check(void) 
{

	if (!etr_eacr.es)

		return;

	if (test_bit(CLOCK_SYNC_ETR, &clock_sync_flags))

	disable_sync_clock(NULL);

	set_bit(ETR_EVENT_SYNC_CHECK, &etr_events);

	queue_work(time_sync_wq, &etr_work);
@@ -914,7 +929,7 @@ static struct etr_eacr etr_handle_update(struct etr_aib *aib, 
	 * Do not try to get the alternate port aib if the clock

	 * is not in sync yet.

	 */

	if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags) && !eacr.es)

	if (!check_sync_clock())

		return eacr;



	/*
@@ -997,7 +1012,6 @@ static void etr_work_fn(struct work_struct *work) 
		on_each_cpu(disable_sync_clock, NULL, 1);

		del_timer_sync(&etr_timer);

		etr_update_eacr(eacr);

		clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags);

		goto out_unlock;

	}
@@ -1071,18 +1085,13 @@ static void etr_work_fn(struct work_struct *work) 
		/* Both ports not usable. */

		eacr.es = eacr.sl = 0;

		sync_port = -1;

		clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags);

	}



	if (!test_bit(CLOCK_SYNC_ETR, &clock_sync_flags))

		eacr.es = 0;



	/*

	 * If the clock is in sync just update the eacr and return.

	 * If there is no valid sync port wait for a port update.

	 */

	if (test_bit(CLOCK_SYNC_STP, &clock_sync_flags) ||

	    eacr.es || sync_port < 0) {

	if (check_sync_clock() || sync_port < 0) {

		etr_update_eacr(eacr);

		etr_set_tolec_timeout(now);

		goto out_unlock;
@@ -1103,13 +1112,11 @@ static void etr_work_fn(struct work_struct *work) 
	 * and set up a timer to try again after 0.5 seconds

	 */

	etr_update_eacr(eacr);

	set_bit(CLOCK_SYNC_ETR, &clock_sync_flags);

	if (now < etr_tolec + (1600000 << 12) ||

	    etr_sync_clock_stop(&aib, sync_port) != 0) {

		/* Sync failed. Try again in 1/2 second. */

		eacr.es = 0;

		etr_update_eacr(eacr);

		clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags);

		etr_set_sync_timeout();

	} else

		etr_set_tolec_timeout(now);
@@ -1191,19 +1198,30 @@ static ssize_t etr_online_store(struct sys_device *dev, 
		return -EINVAL;

	if (!test_bit(CLOCK_SYNC_HAS_ETR, &clock_sync_flags))

		return -EOPNOTSUPP;

	mutex_lock(&clock_sync_mutex);

	if (dev == &etr_port0_dev) {

		if (etr_port0_online == value)

			return count;	/* Nothing to do. */

			goto out;	/* Nothing to do. */

		etr_port0_online = value;

		if (etr_port0_online && etr_port1_online)

			set_bit(CLOCK_SYNC_ETR, &clock_sync_flags);

		else

			clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags);

		set_bit(ETR_EVENT_PORT0_CHANGE, &etr_events);

		queue_work(time_sync_wq, &etr_work);

	} else {

		if (etr_port1_online == value)

			return count;	/* Nothing to do. */

			goto out;	/* Nothing to do. */

		etr_port1_online = value;

		if (etr_port0_online && etr_port1_online)

			set_bit(CLOCK_SYNC_ETR, &clock_sync_flags);

		else

			clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags);

		set_bit(ETR_EVENT_PORT1_CHANGE, &etr_events);

		queue_work(time_sync_wq, &etr_work);

	}

out:

	mutex_unlock(&clock_sync_mutex);

	return count;

}
@@ -1471,8 +1489,6 @@ static void stp_timing_alert(struct stp_irq_parm *intparm) 
 */

void stp_sync_check(void)

{

	if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags))

		return;

	disable_sync_clock(NULL);

	queue_work(time_sync_wq, &stp_work);

}
@@ -1485,8 +1501,6 @@ void stp_sync_check(void) 
 */

void stp_island_check(void)

{

	if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags))

		return;

	disable_sync_clock(NULL);

	queue_work(time_sync_wq, &stp_work);

}
@@ -1513,10 +1527,6 @@ static int stp_sync_clock(void *data) 


	enable_sync_clock();



	set_bit(CLOCK_SYNC_STP, &clock_sync_flags);

	if (test_and_clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags))

		queue_work(time_sync_wq, &etr_work);



	rc = 0;

	if (stp_info.todoff[0] || stp_info.todoff[1] ||

	    stp_info.todoff[2] || stp_info.todoff[3] ||
@@ -1535,9 +1545,6 @@ static int stp_sync_clock(void *data) 
	if (rc) {

		disable_sync_clock(NULL);

		stp_sync->in_sync = -EAGAIN;

		clear_bit(CLOCK_SYNC_STP, &clock_sync_flags);

		if (etr_port0_online || etr_port1_online)

			queue_work(time_sync_wq, &etr_work);

	} else

		stp_sync->in_sync = 1;

	xchg(&first, 0);
@@ -1569,6 +1576,10 @@ static void stp_work_fn(struct work_struct *work) 
	if (rc || stp_info.c == 0)

		goto out_unlock;



	/* Skip synchronization if the clock is already in sync. */

	if (check_sync_clock())

		goto out_unlock;



	memset(&stp_sync, 0, sizeof(stp_sync));

	get_online_cpus();

	atomic_set(&stp_sync.cpus, num_online_cpus() - 1);
@@ -1684,8 +1695,14 @@ static ssize_t stp_online_store(struct sysdev_class *class, 
		return -EINVAL;

	if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))

		return -EOPNOTSUPP;

	mutex_lock(&clock_sync_mutex);

	stp_online = value;

	if (stp_online)

		set_bit(CLOCK_SYNC_STP, &clock_sync_flags);

	else

		clear_bit(CLOCK_SYNC_STP, &clock_sync_flags);

	queue_work(time_sync_wq, &stp_work);

	mutex_unlock(&clock_sync_mutex);

	return count;

}