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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Generic entry points for the idle threads and
  * implementation of the idle task scheduling class.
  *
  * (NOTE: these are not related to SCHED_IDLE batch scheduled
  *        tasks which are handled in sched/fair.c )
  */
 
 /* Linker adds these: start and end of __cpuidle functions */
 extern char __cpuidle_text_start[], __cpuidle_text_end[];
 
 /**
  * sched_idle_set_state - Record idle state for the current CPU.
  * @idle_state: State to record.
  */
 void sched_idle_set_state(struct cpuidle_state *idle_state)
 {
     idle_set_state(this_rq(), idle_state);
 }
 
 static int __read_mostly cpu_idle_force_poll;
 
 void cpu_idle_poll_ctrl(bool enable)
 {
     if (enable) {
         cpu_idle_force_poll++;
     } else {
         cpu_idle_force_poll--;
         WARN_ON_ONCE(cpu_idle_force_poll < 0);
     }
 }
 
 #ifdef CONFIG_GENERIC_IDLE_POLL_SETUP
 static int __init cpu_idle_poll_setup(char *__unused)
 {
     cpu_idle_force_poll = 1;
 
     return 1;
 }
 __setup("nohlt", cpu_idle_poll_setup);
 
 static int __init cpu_idle_nopoll_setup(char *__unused)
 {
     cpu_idle_force_poll = 0;
 
     return 1;
 }
 __setup("hlt", cpu_idle_nopoll_setup);
 #endif
 
 static noinline int __cpuidle cpu_idle_poll(void)
 {
     trace_cpu_idle(0, smp_processor_id());
     stop_critical_timings();
     ct_idle_enter();
     local_irq_enable();
 
     while (!tif_need_resched() &&
            (cpu_idle_force_poll || tick_check_broadcast_expired()))
         cpu_relax();
 
     ct_idle_exit();
     start_critical_timings();
     trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 
     return 1;
 }
 
 /* Weak implementations for optional arch specific functions */
 void __weak arch_cpu_idle_prepare(void) { }
 void __weak arch_cpu_idle_enter(void) { }
 void __weak arch_cpu_idle_exit(void) { }
 void __weak arch_cpu_idle_dead(void) { }
 void __weak arch_cpu_idle(void)
 {
     cpu_idle_force_poll = 1;
     raw_local_irq_enable();
 }
 
 /**
  * default_idle_call - Default CPU idle routine.
  *
  * To use when the cpuidle framework cannot be used.
  */
 void __cpuidle default_idle_call(void)
 {
     if (current_clr_polling_and_test()) {
         local_irq_enable();
     } else {
 
         trace_cpu_idle(1, smp_processor_id());
         stop_critical_timings();
 
         /*
          * arch_cpu_idle() is supposed to enable IRQs, however
          * we can't do that because of RCU and tracing.
          *
          * Trace IRQs enable here, then switch off RCU, and have
          * arch_cpu_idle() use raw_local_irq_enable(). Note that
          * ct_idle_enter() relies on lockdep IRQ state, so switch that
          * last -- this is very similar to the entry code.
          */
         trace_hardirqs_on_prepare();
         lockdep_hardirqs_on_prepare();
         ct_idle_enter();
         lockdep_hardirqs_on(_THIS_IP_);
 
         arch_cpu_idle();
 
         /*
          * OK, so IRQs are enabled here, but RCU needs them disabled to
          * turn itself back on.. funny thing is that disabling IRQs
          * will cause tracing, which needs RCU. Jump through hoops to
          * make it 'work'.
          */
         raw_local_irq_disable();
         lockdep_hardirqs_off(_THIS_IP_);
         ct_idle_exit();
         lockdep_hardirqs_on(_THIS_IP_);
         raw_local_irq_enable();
 
         start_critical_timings();
         trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
     }
 }
 
 static int call_cpuidle_s2idle(struct cpuidle_driver *drv,
                    struct cpuidle_device *dev)
 {
     if (current_clr_polling_and_test())
         return -EBUSY;
 
     return cpuidle_enter_s2idle(drv, dev);
 }
 
 static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev,
               int next_state)
 {
     /*
      * The idle task must be scheduled, it is pointless to go to idle, just
      * update no idle residency and return.
      */
     if (current_clr_polling_and_test()) {
         dev->last_residency_ns = 0;
         local_irq_enable();
         return -EBUSY;
     }
 
     /*
      * Enter the idle state previously returned by the governor decision.
      * This function will block until an interrupt occurs and will take
      * care of re-enabling the local interrupts
      */
     return cpuidle_enter(drv, dev, next_state);
 }
 
 /**
  * cpuidle_idle_call - the main idle function
  *
  * NOTE: no locks or semaphores should be used here
  *
  * On architectures that support TIF_POLLING_NRFLAG, is called with polling
  * set, and it returns with polling set.  If it ever stops polling, it
  * must clear the polling bit.
  */
 static void cpuidle_idle_call(void)
 {
     struct cpuidle_device *dev = cpuidle_get_device();
     struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
     int next_state, entered_state;
 
     /*
      * Check if the idle task must be rescheduled. If it is the
      * case, exit the function after re-enabling the local irq.
      */
     if (need_resched()) {
         local_irq_enable();
         return;
     }
 
     /*
      * The RCU framework needs to be told that we are entering an idle
      * section, so no more rcu read side critical sections and one more
      * step to the grace period
      */
 
     if (cpuidle_not_available(drv, dev)) {
         tick_nohz_idle_stop_tick();
 
         default_idle_call();
         goto exit_idle;
     }
 
     /*
      * Suspend-to-idle ("s2idle") is a system state in which all user space
      * has been frozen, all I/O devices have been suspended and the only
      * activity happens here and in interrupts (if any). In that case bypass
      * the cpuidle governor and go straight for the deepest idle state
      * available.  Possibly also suspend the local tick and the entire
      * timekeeping to prevent timer interrupts from kicking us out of idle
      * until a proper wakeup interrupt happens.
      */
 
     if (idle_should_enter_s2idle() || dev->forced_idle_latency_limit_ns) {
         u64 max_latency_ns;
 
         if (idle_should_enter_s2idle()) {
 
             entered_state = call_cpuidle_s2idle(drv, dev);
             if (entered_state > 0)
                 goto exit_idle;
 
             max_latency_ns = U64_MAX;
         } else {
             max_latency_ns = dev->forced_idle_latency_limit_ns;
         }
 
         tick_nohz_idle_stop_tick();
 
         next_state = cpuidle_find_deepest_state(drv, dev, max_latency_ns);
         call_cpuidle(drv, dev, next_state);
     } else {
         bool stop_tick = true;
 
         /*
          * Ask the cpuidle framework to choose a convenient idle state.
          */
         next_state = cpuidle_select(drv, dev, &stop_tick);
 
         if (stop_tick || tick_nohz_tick_stopped())
             tick_nohz_idle_stop_tick();
         else
             tick_nohz_idle_retain_tick();
 
         entered_state = call_cpuidle(drv, dev, next_state);
         /*
          * Give the governor an opportunity to reflect on the outcome
          */
         cpuidle_reflect(dev, entered_state);
     }
 
 exit_idle:
     __current_set_polling();
 
     /*
      * It is up to the idle functions to reenable local interrupts
      */
     if (WARN_ON_ONCE(irqs_disabled()))
         local_irq_enable();
 }
 
 /*
  * Generic idle loop implementation
  *
  * Called with polling cleared.
  */
 static void do_idle(void)
 {
     int cpu = smp_processor_id();
 
     /*
      * Check if we need to update blocked load
      */
     nohz_run_idle_balance(cpu);
 
     /*
      * If the arch has a polling bit, we maintain an invariant:
      *
      * Our polling bit is clear if we're not scheduled (i.e. if rq->curr !=
      * rq->idle). This means that, if rq->idle has the polling bit set,
      * then setting need_resched is guaranteed to cause the CPU to
      * reschedule.
      */
 
     __current_set_polling();
     tick_nohz_idle_enter();
 
     while (!need_resched()) {
         rmb();
 
         local_irq_disable();
 
         if (cpu_is_offline(cpu)) {
             tick_nohz_idle_stop_tick();
             cpuhp_report_idle_dead();
             arch_cpu_idle_dead();
         }
 
         arch_cpu_idle_enter();
         rcu_nocb_flush_deferred_wakeup();
 
         /*
          * In poll mode we reenable interrupts and spin. Also if we
          * detected in the wakeup from idle path that the tick
          * broadcast device expired for us, we don't want to go deep
          * idle as we know that the IPI is going to arrive right away.
          */
         if (cpu_idle_force_poll || tick_check_broadcast_expired()) {
             tick_nohz_idle_restart_tick();
             cpu_idle_poll();
         } else {
             cpuidle_idle_call();
         }
         arch_cpu_idle_exit();
     }
 
     /*
      * Since we fell out of the loop above, we know TIF_NEED_RESCHED must
      * be set, propagate it into PREEMPT_NEED_RESCHED.
      *
      * This is required because for polling idle loops we will not have had
      * an IPI to fold the state for us.
      */
     preempt_set_need_resched();
     tick_nohz_idle_exit();
     __current_clr_polling();
 
     /*
      * We promise to call sched_ttwu_pending() and reschedule if
      * need_resched() is set while polling is set. That means that clearing
      * polling needs to be visible before doing these things.
      */
     smp_mb__after_atomic();
 
     /*
      * RCU relies on this call to be done outside of an RCU read-side
      * critical section.
      */
     flush_smp_call_function_queue();
     schedule_idle();
 
     if (unlikely(klp_patch_pending(current)))
         klp_update_patch_state(current);
 }
 
 bool cpu_in_idle(unsigned long pc)
 {
     return pc >= (unsigned long)__cpuidle_text_start &&
         pc < (unsigned long)__cpuidle_text_end;
 }
 
 struct idle_timer {
     struct hrtimer timer;
     int done;
 };
 
 static enum hrtimer_restart idle_inject_timer_fn(struct hrtimer *timer)
 {
     struct idle_timer *it = container_of(timer, struct idle_timer, timer);
 
     WRITE_ONCE(it->done, 1);
     set_tsk_need_resched(current);
 
     return HRTIMER_NORESTART;
 }
 
 void play_idle_precise(u64 duration_ns, u64 latency_ns)
 {
     struct idle_timer it;
 
     /*
      * Only FIFO tasks can disable the tick since they don't need the forced
      * preemption.
      */
     WARN_ON_ONCE(current->policy != SCHED_FIFO);
     WARN_ON_ONCE(current->nr_cpus_allowed != 1);
     WARN_ON_ONCE(!(current->flags & PF_KTHREAD));
     WARN_ON_ONCE(!(current->flags & PF_NO_SETAFFINITY));
     WARN_ON_ONCE(!duration_ns);
     WARN_ON_ONCE(current->mm);
 
     rcu_sleep_check();
     preempt_disable();
     current->flags |= PF_IDLE;
     cpuidle_use_deepest_state(latency_ns);
 
     it.done = 0;
     hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
     it.timer.function = idle_inject_timer_fn;
     hrtimer_start(&it.timer, ns_to_ktime(duration_ns),
               HRTIMER_MODE_REL_PINNED_HARD);
 
     while (!READ_ONCE(it.done))
         do_idle();
 
     cpuidle_use_deepest_state(0);
     current->flags &= ~PF_IDLE;
 
     preempt_fold_need_resched();
     preempt_enable();
 }
 EXPORT_SYMBOL_GPL(play_idle_precise);
 
 void cpu_startup_entry(enum cpuhp_state state)
 {
     arch_cpu_idle_prepare();
     cpuhp_online_idle(state);
     while (1)
         do_idle();
 }
 
 /*
  * idle-task scheduling class.
  */
 
 #ifdef CONFIG_SMP
 static int
 select_task_rq_idle(struct task_struct *p, int cpu, int flags)
 {
     return task_cpu(p); /* IDLE tasks as never migrated */
 }
 
 static int
 balance_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 {
     return WARN_ON_ONCE(1);
 }
 #endif
 
 /*
  * Idle tasks are unconditionally rescheduled:
  */
 static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int flags)
 {
     resched_curr(rq);
 }
 
 static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
 {
 }
 
 static void set_next_task_idle(struct rq *rq, struct task_struct *next, bool first)
 {
     update_idle_core(rq);
     schedstat_inc(rq->sched_goidle);
 }
 
 #ifdef CONFIG_SMP
 static struct task_struct *pick_task_idle(struct rq *rq)
 {
     return rq->idle;
 }
 #endif
 
 struct task_struct *pick_next_task_idle(struct rq *rq)
 {
     struct task_struct *next = rq->idle;
 
     set_next_task_idle(rq, next, true);
 
     return next;
 }
 
 /*
  * It is not legal to sleep in the idle task - print a warning
  * message if some code attempts to do it:
  */
 static void
 dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags)
 {
     raw_spin_rq_unlock_irq(rq);
     printk(KERN_ERR "bad: scheduling from the idle thread!\n");
     dump_stack();
     raw_spin_rq_lock_irq(rq);
 }
 
 /*
  * scheduler tick hitting a task of our scheduling class.
  *
  * NOTE: This function can be called remotely by the tick offload that
  * goes along full dynticks. Therefore no local assumption can be made
  * and everything must be accessed through the @rq and @curr passed in
  * parameters.
  */
 static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
 {
 }
 
 static void switched_to_idle(struct rq *rq, struct task_struct *p)
 {
     BUG();
 }
 
 static void
 prio_changed_idle(struct rq *rq, struct task_struct *p, int oldprio)
 {
     BUG();
 }
 
 static void update_curr_idle(struct rq *rq)
 {
 }
 
 /*
  * Simple, special scheduling class for the per-CPU idle tasks:
  */
 DEFINE_SCHED_CLASS(idle) = {
 
     /* no enqueue/yield_task for idle tasks */
 
     /* dequeue is not valid, we print a debug message there: */
     .dequeue_task       = dequeue_task_idle,
 
     .check_preempt_curr = check_preempt_curr_idle,
 
     .pick_next_task     = pick_next_task_idle,
     .put_prev_task      = put_prev_task_idle,
     .set_next_task          = set_next_task_idle,
 
 #ifdef CONFIG_SMP
     .balance        = balance_idle,
     .pick_task      = pick_task_idle,
     .select_task_rq     = select_task_rq_idle,
     .set_cpus_allowed   = set_cpus_allowed_common,
 #endif
 
     .task_tick      = task_tick_idle,
 
     .prio_changed       = prio_changed_idle,
     .switched_to        = switched_to_idle,
     .update_curr        = update_curr_idle,
 };

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