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s390/time: refactor clock sync

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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 <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2016-10-10 09:43:41 +02:00
parent 62ba6f85ee
commit b1c0854d16
3 changed files with 71 additions and 84 deletions
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4
arch/s390/include/asm/timex.h
View File

@ -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 */

2
arch/s390/kernel/early.c
View File

@ -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();

149
arch/s390/kernel/time.c
View File

@ -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;
}