bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
bool test_all)
{
unsigned seq, shared_count;
int ret = true;
retry:
shared_count = 0;
seq = read_seqcount_begin(&obj->seq);
rcu_read_lock();
if (test_all) {
unsigned i;
struct reservation_object_list *fobj = rcu_dereference(obj->fence);
if (fobj)
shared_count = fobj->shared_count;
if (read_seqcount_retry(&obj->seq, seq))
goto unlock_retry;
for (i = 0; i < shared_count; ++i) {
struct fence *fence = rcu_dereference(fobj->shared[i]);
ret = reservation_object_test_signaled_single(fence);
if (ret < 0)
goto unlock_retry;
else if (!ret)
break;
}
/*
* There could be a read_seqcount_retry here, but nothing cares
* about whether it's the old or newer fence pointers that are
* signaled. That race could still have happened after checking
* read_seqcount_retry. If you care, use ww_mutex_lock.
*/
}
if (!shared_count) {
struct fence *fence_excl = rcu_dereference(obj->fence_excl);
if (read_seqcount_retry(&obj->seq, seq))
goto unlock_retry;
if (fence_excl) {
ret = reservation_object_test_signaled_single(fence_excl);
if (ret < 0)
goto unlock_retry;
}
}
rcu_read_unlock();
return ret;
unlock_retry:
rcu_read_unlock();
goto retry;
}
/*
* Setup the device for a periodic tick
*/
void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
{
tick_set_periodic_handler(dev, broadcast);
/* Broadcast setup ? */
if (!tick_device_is_functional(dev))
return;
if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
!tick_broadcast_oneshot_active()) {
clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
} else {
unsigned long seq;
ktime_t next;
do {
seq = read_seqcount_begin(&xtime_seq);
next = tick_next_period;
} while (read_seqcount_retry(&xtime_seq, seq));
clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
for (;;) {
if (!clockevents_program_event(dev, next, ktime_get()))
return;
next = ktime_add(next, tick_period);
}
}
}
u64 get_jiffies_64(void)
{
unsigned long seq;
u64 ret;
do {
seq = read_seqcount_begin(&jiffies_seq);
ret = jiffies_64;
} while (read_seqcount_retry(&jiffies_seq, seq));
return ret;
}
cputime64_t arch_cpu_idle_time(int cpu)
{
struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
unsigned long long now, idle_enter, idle_exit;
unsigned int seq;
do {
now = get_tod_clock();
seq = read_seqcount_begin(&idle->seqcount);
idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
idle_exit = ACCESS_ONCE(idle->clock_idle_exit);
} while (read_seqcount_retry(&idle->seqcount, seq));
return idle_enter ? ((idle_exit ?: now) - idle_enter) : 0;
}
static ssize_t show_idle_count(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
unsigned long long idle_count;
unsigned int seq;
do {
seq = read_seqcount_begin(&idle->seqcount);
idle_count = ACCESS_ONCE(idle->idle_count);
if (ACCESS_ONCE(idle->clock_idle_enter))
idle_count++;
} while (read_seqcount_retry(&idle->seqcount, seq));
return sprintf(buf, "%llu\n", idle_count);
}
static ssize_t show_idle_time(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
unsigned long long now, idle_time, idle_enter, idle_exit;
unsigned int seq;
do {
now = get_tod_clock();
seq = read_seqcount_begin(&idle->seqcount);
idle_time = ACCESS_ONCE(idle->idle_time);
idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
idle_exit = ACCESS_ONCE(idle->clock_idle_exit);
} while (read_seqcount_retry(&idle->seqcount, seq));
idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0;
return sprintf(buf, "%llu\n", idle_time >> 12);
}
/*
* A timer is active, when it is enqueued into the rbtree or the
* callback function is running or it's in the state of being migrated
* to another cpu.
*
* It is important for this function to not return a false negative.
*/
bool hrtimer_active(const struct hrtimer *timer)
{
struct hrtimer_cpu_base *cpu_base;
unsigned int seq;
do {
cpu_base = READ_ONCE(timer->base->cpu_base);
seq = raw_read_seqcount_begin(&cpu_base->seq);
if (timer->state != HRTIMER_STATE_INACTIVE ||
cpu_base->running == timer)
return true;
} while (read_seqcount_retry(&cpu_base->seq, seq) ||
cpu_base != READ_ONCE(timer->base->cpu_base));
return false;
}
void
__gnet_stats_copy_basic(const seqcount_t *running,
struct gnet_stats_basic_packed *bstats,
struct gnet_stats_basic_cpu __percpu *cpu,
struct gnet_stats_basic_packed *b)
{
unsigned int seq;
if (cpu) {
__gnet_stats_copy_basic_cpu(bstats, cpu);
return;
}
do {
if (running)
seq = read_seqcount_begin(running);
bstats->bytes = b->bytes;
bstats->packets = b->packets;
} while (running && read_seqcount_retry(running, seq));
}
bool gen_estimator_read(struct net_rate_estimator __rcu **rate_est,
struct gnet_stats_rate_est64 *sample)
{
struct net_rate_estimator *est;
unsigned seq;
rcu_read_lock();
est = rcu_dereference(*rate_est);
if (!est) {
rcu_read_unlock();
return false;
}
do {
seq = read_seqcount_begin(&est->seq);
sample->bps = est->avbps >> 8;
sample->pps = est->avpps >> 8;
} while (read_seqcount_retry(&est->seq, seq));
rcu_read_unlock();
return true;
}
static void get_recent_times(struct psi_group *group, int cpu, u32 *times)
{
struct psi_group_cpu *groupc = per_cpu_ptr(group->pcpu, cpu);
unsigned int tasks[NR_PSI_TASK_COUNTS];
u64 now, state_start;
unsigned int seq;
int s;
/* Snapshot a coherent view of the CPU state */
do {
seq = read_seqcount_begin(&groupc->seq);
now = cpu_clock(cpu);
memcpy(times, groupc->times, sizeof(groupc->times));
memcpy(tasks, groupc->tasks, sizeof(groupc->tasks));
state_start = groupc->state_start;
} while (read_seqcount_retry(&groupc->seq, seq));
/* Calculate state time deltas against the previous snapshot */
for (s = 0; s < NR_PSI_STATES; s++) {
u32 delta;
/*
* In addition to already concluded states, we also
* incorporate currently active states on the CPU,
* since states may last for many sampling periods.
*
* This way we keep our delta sampling buckets small
* (u32) and our reported pressure close to what's
* actually happening.
*/
if (test_state(tasks, s))
times[s] += now - state_start;
delta = times[s] - groupc->times_prev[s];
groupc->times_prev[s] = times[s];
times[s] = delta;
}
}
static void nft_counter_fetch(struct nft_counter_percpu_priv *priv,
struct nft_counter *total)
{
struct nft_counter *this_cpu;
const seqcount_t *myseq;
u64 bytes, packets;
unsigned int seq;
int cpu;
memset(total, 0, sizeof(*total));
for_each_possible_cpu(cpu) {
myseq = per_cpu_ptr(&nft_counter_seq, cpu);
this_cpu = per_cpu_ptr(priv->counter, cpu);
do {
seq = read_seqcount_begin(myseq);
bytes = this_cpu->bytes;
packets = this_cpu->packets;
} while (read_seqcount_retry(myseq, seq));
total->bytes += bytes;
total->packets += packets;
}
}
/**
* tick_nohz_stop_sched_tick - stop the idle tick from the idle task
*
* When the next event is more than a tick into the future, stop the idle tick
* Called either from the idle loop or from irq_exit() when an idle period was
* just interrupted by an interrupt which did not cause a reschedule.
*/
void tick_nohz_stop_sched_tick(int inidle)
{
unsigned long seq, last_jiffies, next_jiffies, delta_jiffies, flags;
struct tick_sched *ts;
ktime_t last_update, expires, now;
struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
u64 time_delta;
int cpu;
local_irq_save(flags);
cpu = smp_processor_id();
ts = &per_cpu(tick_cpu_sched, cpu);
/*
* Call to tick_nohz_start_idle stops the last_update_time from being
* updated. Thus, it must not be called in the event we are called from
* irq_exit() with the prior state different than idle.
*/
if (!inidle && !ts->inidle)
goto end;
/*
* Set ts->inidle unconditionally. Even if the system did not
* switch to NOHZ mode the cpu frequency governers rely on the
* update of the idle time accounting in tick_nohz_start_idle().
*/
ts->inidle = 1;
now = tick_nohz_start_idle(cpu, ts);
/*
* If this cpu is offline and it is the one which updates
* jiffies, then give up the assignment and let it be taken by
* the cpu which runs the tick timer next. If we don't drop
* this here the jiffies might be stale and do_timer() never
* invoked.
*/
if (unlikely(!cpu_online(cpu))) {
if (cpu == tick_do_timer_cpu)
tick_do_timer_cpu = TICK_DO_TIMER_NONE;
}
if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
goto end;
if (need_resched())
goto end;
if (unlikely(local_softirq_pending() && cpu_online(cpu))) {
softirq_check_pending_idle();
goto end;
}
ts->idle_calls++;
/* Read jiffies and the time when jiffies were updated last */
do {
seq = read_seqcount_begin(&xtime_seq);
last_update = last_jiffies_update;
last_jiffies = jiffies;
time_delta = timekeeping_max_deferment();
} while (read_seqcount_retry(&xtime_seq, seq));
if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||
arch_needs_cpu(cpu)) {
next_jiffies = last_jiffies + 1;
delta_jiffies = 1;
} else {
/* Get the next timer wheel timer */
next_jiffies = get_next_timer_interrupt(last_jiffies);
delta_jiffies = next_jiffies - last_jiffies;
}
/*
* Do not stop the tick, if we are only one off
* or if the cpu is required for rcu
*/
if (!ts->tick_stopped && delta_jiffies == 1)
goto out;
/* Schedule the tick, if we are at least one jiffie off */
if ((long)delta_jiffies >= 1) {
/*
* If this cpu is the one which updates jiffies, then
* give up the assignment and let it be taken by the
* cpu which runs the tick timer next, which might be
* this cpu as well. If we don't drop this here the
* jiffies might be stale and do_timer() never
* invoked. Keep track of the fact that it was the one
* which had the do_timer() duty last. If this cpu is
* the one which had the do_timer() duty last, we
* limit the sleep time to the timekeeping
* max_deferement value which we retrieved
* above. Otherwise we can sleep as long as we want.
*/
if (cpu == tick_do_timer_cpu) {
tick_do_timer_cpu = TICK_DO_TIMER_NONE;
ts->do_timer_last = 1;
} else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {
time_delta = KTIME_MAX;
ts->do_timer_last = 0;
} else if (!ts->do_timer_last) {
time_delta = KTIME_MAX;
}
/*
* calculate the expiry time for the next timer wheel
* timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals
* that there is no timer pending or at least extremely
* far into the future (12 days for HZ=1000). In this
* case we set the expiry to the end of time.
*/
if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) {
/*
* Calculate the time delta for the next timer event.
* If the time delta exceeds the maximum time delta
* permitted by the current clocksource then adjust
* the time delta accordingly to ensure the
* clocksource does not wrap.
*/
time_delta = min_t(u64, time_delta,
tick_period.tv64 * delta_jiffies);
}
if (time_delta < KTIME_MAX)
expires = ktime_add_ns(last_update, time_delta);
else
expires.tv64 = KTIME_MAX;
if (delta_jiffies > 1)
cpumask_set_cpu(cpu, nohz_cpu_mask);
/* Skip reprogram of event if its not changed */
if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
goto out;
/*
* nohz_stop_sched_tick can be called several times before
* the nohz_restart_sched_tick is called. This happens when
* interrupts arrive which do not cause a reschedule. In the
* first call we save the current tick time, so we can restart
* the scheduler tick in nohz_restart_sched_tick.
*/
if (!ts->tick_stopped) {
select_nohz_load_balancer(1);
ts->idle_tick = hrtimer_get_expires(&ts->sched_timer);
ts->tick_stopped = 1;
ts->idle_jiffies = last_jiffies;
rcu_enter_nohz();
}
ts->idle_sleeps++;
/* Mark expires */
ts->idle_expires = expires;
/*
* If the expiration time == KTIME_MAX, then
* in this case we simply stop the tick timer.
*/
if (unlikely(expires.tv64 == KTIME_MAX)) {
if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
hrtimer_cancel(&ts->sched_timer);
goto out;
}
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start(&ts->sched_timer, expires,
HRTIMER_MODE_ABS_PINNED);
/* Check, if the timer was already in the past */
if (hrtimer_active(&ts->sched_timer))
goto out;
} else if (!tick_program_event(expires, 0))
goto out;
/*
* We are past the event already. So we crossed a
* jiffie boundary. Update jiffies and raise the
* softirq.
*/
tick_do_update_jiffies64(ktime_get());
cpumask_clear_cpu(cpu, nohz_cpu_mask);
}
raise_softirq_irqoff(TIMER_SOFTIRQ);
out:
ts->next_jiffies = next_jiffies;
ts->last_jiffies = last_jiffies;
ts->sleep_length = ktime_sub(dev->next_event, now);
end:
local_irq_restore(flags);
}
long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
bool wait_all, bool intr,
unsigned long timeout)
{
struct fence *fence;
unsigned seq, shared_count, i = 0;
long ret = timeout;
retry:
fence = NULL;
shared_count = 0;
seq = read_seqcount_begin(&obj->seq);
rcu_read_lock();
if (wait_all) {
struct reservation_object_list *fobj = rcu_dereference(obj->fence);
if (fobj)
shared_count = fobj->shared_count;
if (read_seqcount_retry(&obj->seq, seq))
goto unlock_retry;
for (i = 0; i < shared_count; ++i) {
struct fence *lfence = rcu_dereference(fobj->shared[i]);
if (test_bit(FENCE_FLAG_SIGNALED_BIT, &lfence->flags))
continue;
if (!fence_get_rcu(lfence))
goto unlock_retry;
if (fence_is_signaled(lfence)) {
fence_put(lfence);
continue;
}
fence = lfence;
break;
}
}
if (!shared_count) {
struct fence *fence_excl = rcu_dereference(obj->fence_excl);
if (read_seqcount_retry(&obj->seq, seq))
goto unlock_retry;
if (fence_excl &&
!test_bit(FENCE_FLAG_SIGNALED_BIT, &fence_excl->flags)) {
if (!fence_get_rcu(fence_excl))
goto unlock_retry;
if (fence_is_signaled(fence_excl))
fence_put(fence_excl);
else
fence = fence_excl;
}
}
rcu_read_unlock();
if (fence) {
ret = fence_wait_timeout(fence, intr, ret);
fence_put(fence);
if (ret > 0 && wait_all && (i + 1 < shared_count))
goto retry;
}
return ret;
unlock_retry:
rcu_read_unlock();
goto retry;
}
int reservation_object_get_fences_rcu(struct reservation_object *obj,
struct fence **pfence_excl,
unsigned *pshared_count,
struct fence ***pshared)
{
unsigned shared_count = 0;
unsigned retry = 1;
struct fence **shared = NULL, *fence_excl = NULL;
int ret = 0;
while (retry) {
struct reservation_object_list *fobj;
unsigned seq;
seq = read_seqcount_begin(&obj->seq);
rcu_read_lock();
fobj = rcu_dereference(obj->fence);
if (fobj) {
struct fence **nshared;
size_t sz = sizeof(*shared) * fobj->shared_max;
nshared = krealloc(shared, sz,
GFP_NOWAIT | __GFP_NOWARN);
if (!nshared) {
rcu_read_unlock();
nshared = krealloc(shared, sz, GFP_KERNEL);
if (nshared) {
shared = nshared;
continue;
}
ret = -ENOMEM;
shared_count = 0;
break;
}
shared = nshared;
memcpy(shared, fobj->shared, sz);
shared_count = fobj->shared_count;
} else
shared_count = 0;
fence_excl = rcu_dereference(obj->fence_excl);
retry = read_seqcount_retry(&obj->seq, seq);
if (retry)
goto unlock;
if (!fence_excl || fence_get_rcu(fence_excl)) {
unsigned i;
for (i = 0; i < shared_count; ++i) {
if (fence_get_rcu(shared[i]))
continue;
/* uh oh, refcount failed, abort and retry */
while (i--)
fence_put(shared[i]);
if (fence_excl) {
fence_put(fence_excl);
fence_excl = NULL;
}
retry = 1;
break;
}
} else
retry = 1;
unlock:
rcu_read_unlock();
}
*pshared_count = shared_count;
if (shared_count)
*pshared = shared;
else {
*pshared = NULL;
kfree(shared);
}
*pfence_excl = fence_excl;
return ret;
}
