From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> 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: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> --- arch/s390/kernel/time.c | 71 +++++++++++++++++++++++++++++------------------- 1 file changed, 44 insertions(+), 27 deletions(-) Index: quilt-2.6/arch/s390/kernel/time.c =================================================================== --- quilt-2.6.orig/arch/s390/kernel/time.c +++ quilt-2.6/arch/s390/kernel/time.c @@ -331,6 +331,7 @@ static unsigned long long adjust_time(un } 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"); @@ -533,8 +550,7 @@ void etr_switch_to_local(void) { if (!etr_eacr.sl) return; - if (test_bit(CLOCK_SYNC_ETR, &clock_sync_flags)) - disable_sync_clock(NULL); + disable_sync_clock(NULL); set_bit(ETR_EVENT_SWITCH_LOCAL, &etr_events); queue_work(time_sync_wq, &etr_work); } @@ -549,8 +565,7 @@ void etr_sync_check(void) { if (!etr_eacr.es) return; - if (test_bit(CLOCK_SYNC_ETR, &clock_sync_flags)) - disable_sync_clock(NULL); + 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 * 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_stru 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_stru /* 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_stru * 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 s 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_ */ 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_stru 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 s 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; } -- blue skies, Martin. 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