From b1c0854d168cc5741e9568556e7d7cc3873c9cdc Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 10 Oct 2016 09:43:41 +0200 Subject: [PATCH] s390/time: refactor clock sync Merge clock_sync_cpu into stp_sync_clock and split out the update of the global and per-CPU clock fields into clock_sync_global and clock_sync_local. Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/timex.h | 4 +- arch/s390/kernel/early.c | 2 +- arch/s390/kernel/time.c | 149 ++++++++++++++++------------------ 3 files changed, 71 insertions(+), 84 deletions(-) diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h index 0bb08f341c09..b62d8c4ec022 100644 --- a/arch/s390/include/asm/timex.h +++ b/arch/s390/include/asm/timex.h @@ -52,11 +52,9 @@ static inline void store_clock_comparator(__u64 *time) void clock_comparator_work(void); -void __init ptff_init(void); +void __init time_early_init(void); extern unsigned char ptff_function_mask[16]; -extern unsigned long lpar_offset; -extern unsigned long initial_leap_seconds; /* Function codes for the ptff instruction. */ #define PTFF_QAF 0x00 /* query available functions */ diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c index 2374c5b46bbc..39d03a7a3354 100644 --- a/arch/s390/kernel/early.c +++ b/arch/s390/kernel/early.c @@ -467,7 +467,7 @@ void __init startup_init(void) ipl_save_parameters(); rescue_initrd(); clear_bss_section(); - ptff_init(); + time_early_init(); init_kernel_storage_key(); lockdep_off(); setup_lowcore_early(); diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index 0bfcc492987e..a8f1bad30fc9 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -59,13 +59,14 @@ ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier); EXPORT_SYMBOL(s390_epoch_delta_notifier); unsigned char ptff_function_mask[16]; -unsigned long lpar_offset; -unsigned long initial_leap_seconds; + +static unsigned long long lpar_offset; +static unsigned long long initial_leap_seconds; /* * Get time offsets with PTFF */ -void __init ptff_init(void) +void __init time_early_init(void) { struct ptff_qto qto; struct ptff_qui qui; @@ -80,7 +81,7 @@ void __init ptff_init(void) /* get initial leap seconds */ if (ptff_query(PTFF_QUI) && ptff(&qui, sizeof(qui), PTFF_QUI) == 0) - initial_leap_seconds = (unsigned long) + initial_leap_seconds = (unsigned long long) ((long) qui.old_leap * 4096000000L); } @@ -123,18 +124,6 @@ void clock_comparator_work(void) cd->event_handler(cd); } -/* - * Fixup the clock comparator. - */ -static void fixup_clock_comparator(unsigned long long delta) -{ - /* If nobody is waiting there's nothing to fix. */ - if (S390_lowcore.clock_comparator == -1ULL) - return; - S390_lowcore.clock_comparator += delta; - set_clock_comparator(S390_lowcore.clock_comparator); -} - static int s390_next_event(unsigned long delta, struct clock_event_device *evt) { @@ -384,6 +373,36 @@ static inline int check_sync_clock(void) return rc; } +/* + * Apply clock delta to the global data structures. + * This is called once on the CPU that performed the clock sync. + */ +static void clock_sync_global(unsigned long long delta) +{ + struct ptff_qto qto; + + /* Fixup the monotonic sched clock. */ + sched_clock_base_cc += delta; + /* Update LPAR offset. */ + if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0) + lpar_offset = qto.tod_epoch_difference; + /* Call the TOD clock change notifier. */ + atomic_notifier_call_chain(&s390_epoch_delta_notifier, 0, &delta); +} + +/* + * Apply clock delta to the per-CPU data structures of this CPU. + * This is called for each online CPU after the call to clock_sync_global. + */ +static void clock_sync_local(unsigned long long delta) +{ + /* Add the delta to the clock comparator. */ + if (S390_lowcore.clock_comparator != -1ULL) { + S390_lowcore.clock_comparator += delta; + set_clock_comparator(S390_lowcore.clock_comparator); + } +} + /* Single threaded workqueue used for stp sync events */ static struct workqueue_struct *time_sync_wq; @@ -397,31 +416,9 @@ static void __init time_init_wq(void) struct clock_sync_data { atomic_t cpus; int in_sync; - unsigned long long fixup_cc; + unsigned long long clock_delta; }; -static void clock_sync_cpu(struct clock_sync_data *sync) -{ - atomic_dec(&sync->cpus); - enable_sync_clock(); - while (sync->in_sync == 0) { - __udelay(1); - /* - * A different cpu changes *in_sync. Therefore use - * barrier() to force memory access. - */ - barrier(); - } - if (sync->in_sync != 1) - /* Didn't work. Clear per-cpu in sync bit again. */ - disable_sync_clock(NULL); - /* - * This round of TOD syncing is done. Set the clock comparator - * to the next tick and let the processor continue. - */ - fixup_clock_comparator(sync->fixup_cc); -} - /* * Server Time Protocol (STP) code. */ @@ -523,54 +520,46 @@ void stp_queue_work(void) static int stp_sync_clock(void *data) { - static int first; + struct clock_sync_data *sync = data; unsigned long long clock_delta; - struct clock_sync_data *stp_sync; - struct ptff_qto qto; + static int first; int rc; - stp_sync = data; - - if (xchg(&first, 1) == 1) { - /* Slave */ - clock_sync_cpu(stp_sync); - return 0; - } - - /* Wait until all other cpus entered the sync function. */ - while (atomic_read(&stp_sync->cpus) != 0) - cpu_relax(); - enable_sync_clock(); - - rc = 0; - if (stp_info.todoff[0] || stp_info.todoff[1] || - stp_info.todoff[2] || stp_info.todoff[3] || - stp_info.tmd != 2) { - rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0, &clock_delta); - if (rc == 0) { - /* fixup the monotonic sched clock */ - sched_clock_base_cc += clock_delta; - if (ptff_query(PTFF_QTO) && - ptff(&qto, sizeof(qto), PTFF_QTO) == 0) - /* Update LPAR offset */ - lpar_offset = qto.tod_epoch_difference; - atomic_notifier_call_chain(&s390_epoch_delta_notifier, - 0, &clock_delta); - stp_sync->fixup_cc = clock_delta; - fixup_clock_comparator(clock_delta); - rc = chsc_sstpi(stp_page, &stp_info, - sizeof(struct stp_sstpi)); - if (rc == 0 && stp_info.tmd != 2) - rc = -EAGAIN; + if (xchg(&first, 1) == 0) { + /* Wait until all other cpus entered the sync function. */ + while (atomic_read(&sync->cpus) != 0) + cpu_relax(); + rc = 0; + if (stp_info.todoff[0] || stp_info.todoff[1] || + stp_info.todoff[2] || stp_info.todoff[3] || + stp_info.tmd != 2) { + rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0, + &clock_delta); + if (rc == 0) { + sync->clock_delta = clock_delta; + clock_sync_global(clock_delta); + rc = chsc_sstpi(stp_page, &stp_info, + sizeof(struct stp_sstpi)); + if (rc == 0 && stp_info.tmd != 2) + rc = -EAGAIN; + } } + sync->in_sync = rc ? -EAGAIN : 1; + xchg(&first, 0); + } else { + /* Slave */ + atomic_dec(&sync->cpus); + /* Wait for in_sync to be set. */ + while (READ_ONCE(sync->in_sync) == 0) + __udelay(1); } - if (rc) { + if (sync->in_sync != 1) + /* Didn't work. Clear per-cpu in sync bit again. */ disable_sync_clock(NULL); - stp_sync->in_sync = -EAGAIN; - } else - stp_sync->in_sync = 1; - xchg(&first, 0); + /* Apply clock delta to per-CPU fields of this CPU. */ + clock_sync_local(sync->clock_delta); + return 0; } -- 2.45.2