sched/smp: Make SMP unconditional

Simplify the scheduler by making CONFIG_SMP=y primitives and data
structures unconditional.

Introduce transitory wrappers for functionality not yet converted to SMP.

Note that this patch is pretty large, because there's no clear separation
between various aspects of the SMP scheduler, it's basically a huge block
of #ifdef CONFIG_SMP. A fair amount of it has to be switched on for it to
boot and work on UP systems.

Signed-off-by: Ingo Molnar <[e-mail]>
Acked-by: Peter Zijlstra <[e-mail]>
Cc: Dietmar Eggemann <[e-mail]>
Cc: Juri Lelli <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Mel Gorman <[e-mail]>
Cc: Sebastian Andrzej Siewior <[e-mail]>
Cc: Shrikanth Hegde <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Cc: Valentin Schneider <[e-mail]>
Cc: Vincent Guittot <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

include/linux/preempt.h

···
 
 #endif
 
-#ifdef CONFIG_SMP
-
 /*
  * Migrate-Disable and why it is undesired.
  *
···
  */
 extern void migrate_disable(void);
 extern void migrate_enable(void);
-
-#else
-
-static inline void migrate_disable(void) { }
-static inline void migrate_enable(void) { }
-
-#endif /* CONFIG_SMP */
 
 /**
  * preempt_disable_nested - Disable preemption inside a normally preempt disabled section

include/linux/sched.h

···
 	unsigned long			runnable_weight;
 #endif
 
-#ifdef CONFIG_SMP
 	/*
 	 * Per entity load average tracking.
 	 *
···
 	 * collide with read-mostly values above.
 	 */
 	struct sched_avg		avg;
-#endif
 };
 
 struct sched_rt_entity {
···
 	struct alloc_tag		*alloc_tag;
 #endif
 
-#ifdef CONFIG_SMP
 	int				on_cpu;
 	struct __call_single_node	wake_entry;
 	unsigned int			wakee_flips;
···
 	 */
 	int				recent_used_cpu;
 	int				wake_cpu;
-#endif
 	int				on_rq;
 
 	int				prio;
···
 	cpumask_t			*user_cpus_ptr;
 	cpumask_t			cpus_mask;
 	void				*migration_pending;
-#ifdef CONFIG_SMP
 	unsigned short			migration_disabled;
-#endif
 	unsigned short			migration_flags;
 
 #ifdef CONFIG_PREEMPT_RCU
···
 	struct sched_info		sched_info;
 
 	struct list_head		tasks;
-#ifdef CONFIG_SMP
 	struct plist_node		pushable_tasks;
 	struct rb_node			pushable_dl_tasks;
-#endif
 
 	struct mm_struct		*mm;
 	struct mm_struct		*active_mm;
···
 extern int task_can_attach(struct task_struct *p);
 extern int dl_bw_alloc(int cpu, u64 dl_bw);
 extern void dl_bw_free(int cpu, u64 dl_bw);
-#ifdef CONFIG_SMP
 
 /* do_set_cpus_allowed() - consider using set_cpus_allowed_ptr() instead */
 extern void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask);
···
 extern int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask);
 extern void force_compatible_cpus_allowed_ptr(struct task_struct *p);
 extern void relax_compatible_cpus_allowed_ptr(struct task_struct *p);
-#else
-static inline void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
-{
-}
-static inline int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
-{
-	/* Opencoded cpumask_test_cpu(0, new_mask) to avoid dependency on cpumask.h */
-	if ((*cpumask_bits(new_mask) & 1) == 0)
-		return -EINVAL;
-	return 0;
-}
-static inline int dup_user_cpus_ptr(struct task_struct *dst, struct task_struct *src, int node)
-{
-	if (src->user_cpus_ptr)
-		return -EINVAL;
-	return 0;
-}
-static inline void release_user_cpus_ptr(struct task_struct *p)
-{
-	WARN_ON(p->user_cpus_ptr);
-}
-
-static inline int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask)
-{
-	return 0;
-}
-#endif
 
 extern int yield_to(struct task_struct *p, bool preempt);
 extern void set_user_nice(struct task_struct *p, long nice);
···
 extern int wake_up_process(struct task_struct *tsk);
 extern void wake_up_new_task(struct task_struct *tsk);
 
-#ifdef CONFIG_SMP
 extern void kick_process(struct task_struct *tsk);
-#else
-static inline void kick_process(struct task_struct *tsk) { }
-#endif
 
 extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec);
 #define set_task_comm(tsk, from) ({			\
···
 #define TASK_SIZE_OF(tsk)	TASK_SIZE
 #endif
 
-#ifdef CONFIG_SMP
 static inline bool owner_on_cpu(struct task_struct *owner)
 {
 	/*
···
 
 /* Returns effective CPU energy utilization, as seen by the scheduler */
 unsigned long sched_cpu_util(int cpu);
-#endif /* CONFIG_SMP */
 
 #ifdef CONFIG_SCHED_CORE
 extern void sched_core_free(struct task_struct *tsk);

include/linux/sched/deadline.h

···
 	return (s64)(a - b) < 0;
 }
 
-#ifdef CONFIG_SMP
-
 struct root_domain;
 extern void dl_add_task_root_domain(struct task_struct *p);
 extern void dl_clear_root_domain(struct root_domain *rd);
 extern void dl_clear_root_domain_cpu(int cpu);
-
-#endif /* CONFIG_SMP */
 
 extern u64 dl_cookie;
 extern bool dl_bw_visited(int cpu, u64 cookie);

include/linux/sched/idle.h

···
 	CPU_MAX_IDLE_TYPES
 };
 
-#ifdef CONFIG_SMP
 extern void wake_up_if_idle(int cpu);
-#else
-static inline void wake_up_if_idle(int cpu) { }
-#endif
 
 /*
  * Idle thread specific functions to determine the need_resched

include/linux/sched/nohz.h

···
  * This is the interface between the scheduler and nohz/dynticks:
  */
 
-#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
+#ifdef CONFIG_NO_HZ_COMMON
 extern void nohz_balance_enter_idle(int cpu);
 extern int get_nohz_timer_target(void);
 #else
···
 static inline void calc_load_nohz_stop(void) { }
 #endif /* CONFIG_NO_HZ_COMMON */
 
-#if defined(CONFIG_NO_HZ_COMMON) && defined(CONFIG_SMP)
+#ifdef CONFIG_NO_HZ_COMMON
 extern void wake_up_nohz_cpu(int cpu);
 #else
 static inline void wake_up_nohz_cpu(int cpu) { }

include/linux/sched/topology.h

···
 /*
  * sched-domains (multiprocessor balancing) declarations:
  */
-#ifdef CONFIG_SMP
 
 /* Generate SD flag indexes */
 #define SD_FLAG(name, mflags) __##name,
···
 
 
 # define SD_INIT_NAME(type)		.name = #type
-
-#else /* CONFIG_SMP */
-
-struct sched_domain_attr;
-
-static inline void
-partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
-			struct sched_domain_attr *dattr_new)
-{
-}
-
-static inline bool cpus_equal_capacity(int this_cpu, int that_cpu)
-{
-	return true;
-}
-
-static inline bool cpus_share_cache(int this_cpu, int that_cpu)
-{
-	return true;
-}
-
-static inline bool cpus_share_resources(int this_cpu, int that_cpu)
-{
-	return true;
-}
-
-static inline void sched_update_asym_prefer_cpu(int cpu, int old_prio, int new_prio)
-{
-}
-
-#endif	/* !CONFIG_SMP */
 
 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
 extern void rebuild_sched_domains_energy(void);

kernel/sched/build_policy.c

···
 #include "idle.c"
 
 #include "rt.c"
+#include "cpudeadline.c"
 
-#ifdef CONFIG_SMP
-# include "cpudeadline.c"
-# include "pelt.c"
-#endif
+#include "pelt.c"
 
 #include "cputime.c"
 #include "deadline.c"

kernel/sched/build_utility.c

···
 #include "wait_bit.c"
 #include "wait.c"
 
-#ifdef CONFIG_SMP
-# include "cpupri.c"
-# include "stop_task.c"
-#endif
+#include "cpupri.c"
+#include "stop_task.c"
 
 #include "topology.c"
 

kernel/sched/core.c

···
 	raw_spin_unlock(rq_lockp(rq));
 }
 
-#ifdef CONFIG_SMP
 /*
  * double_rq_lock - safely lock two runqueues
  */
···
 
 	double_rq_clock_clear_update(rq1, rq2);
 }
-#endif /* CONFIG_SMP */
 
 /*
  * __task_rq_lock - lock the rq @p resides on.
···
 	_val;								\
 })
 
-#if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
+#ifdef TIF_POLLING_NRFLAG
 /*
  * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
  * this avoids any races wrt polling state changes and thereby avoids
···
 	return true;
 }
 
-#ifdef CONFIG_SMP
 static inline bool set_nr_if_polling(struct task_struct *p)
 {
 	return false;
 }
-#endif
 #endif
 
 static bool __wake_q_add(struct wake_q_head *head, struct task_struct *task)
···
 	raw_spin_rq_unlock_irqrestore(rq, flags);
 }
 
-#ifdef CONFIG_SMP
 #ifdef CONFIG_NO_HZ_COMMON
 /*
  * In the semi idle case, use the nearest busy CPU for migrating timers
···
 	return true;
 }
 #endif /* CONFIG_NO_HZ_FULL */
-#endif /* CONFIG_SMP */
 
-#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
-			(defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
+#if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_FAIR_GROUP_SCHED)
 /*
  * Iterate task_group tree rooted at *from, calling @down when first entering a
  * node and @up when leaving it for the final time.
···
 	return ncsw;
 }
 
-#ifdef CONFIG_SMP
-
 static void
 __do_set_cpus_allowed(struct task_struct *p, struct affinity_context *ctx);
 
···
 	WARN_ON_ONCE(ret);
 }
 
+#ifdef CONFIG_SMP
+
 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 {
 	unsigned int state = READ_ONCE(p->__state);
···
 
 	__set_task_cpu(p, new_cpu);
 }
+#endif /* CONFIG_SMP */
 
 #ifdef CONFIG_NUMA_BALANCING
 static void __migrate_swap_task(struct task_struct *p, int cpu)
···
 	}
 }
 
-#else /* !CONFIG_SMP: */
-
-static inline void migrate_disable_switch(struct rq *rq, struct task_struct *p) { }
-
-static inline bool rq_has_pinned_tasks(struct rq *rq)
-{
-	return false;
-}
-
-#endif /* !CONFIG_SMP */
-
 static void
 ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
 {
···
 
 	rq = this_rq();
 
-#ifdef CONFIG_SMP
 	if (cpu == rq->cpu) {
 		__schedstat_inc(rq->ttwu_local);
 		__schedstat_inc(p->stats.nr_wakeups_local);
···
 
 	if (wake_flags & WF_MIGRATED)
 		__schedstat_inc(p->stats.nr_wakeups_migrate);
-#endif /* CONFIG_SMP */
 
 	__schedstat_inc(rq->ttwu_count);
 	__schedstat_inc(p->stats.nr_wakeups);
···
 	if (p->sched_contributes_to_load)
 		rq->nr_uninterruptible--;
 
-#ifdef CONFIG_SMP
 	if (wake_flags & WF_RQ_SELECTED)
 		en_flags |= ENQUEUE_RQ_SELECTED;
 	if (wake_flags & WF_MIGRATED)
 		en_flags |= ENQUEUE_MIGRATED;
 	else
-#endif
 	if (p->in_iowait) {
 		delayacct_blkio_end(p);
 		atomic_dec(&task_rq(p)->nr_iowait);
···
 
 	ttwu_do_wakeup(p);
 
-#ifdef CONFIG_SMP
 	if (p->sched_class->task_woken) {
 		/*
 		 * Our task @p is fully woken up and running; so it's safe to
···
 
 		rq->idle_stamp = 0;
 	}
-#endif /* CONFIG_SMP */
 }
 
 /*
···
 	return ret;
 }
 
-#ifdef CONFIG_SMP
 void sched_ttwu_pending(void *arg)
 {
 	struct llist_node *llist = arg;
···
 	p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
 
 	WRITE_ONCE(rq->ttwu_pending, 1);
+#ifdef CONFIG_SMP
 	__smp_call_single_queue(cpu, &p->wake_entry.llist);
+#endif
 }
 
 void wake_up_if_idle(int cpu)
···
 
 	return false;
 }
-
-#else /* !CONFIG_SMP: */
-
-static inline bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
-{
-	return false;
-}
-
-#endif /* !CONFIG_SMP */
 
 static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
 {
···
 	p->capture_control = NULL;
 #endif
 	init_numa_balancing(clone_flags, p);
-#ifdef CONFIG_SMP
 	p->wake_entry.u_flags = CSD_TYPE_TTWU;
 	p->migration_pending = NULL;
-#endif
 	init_sched_mm_cid(p);
 }
 
···
 	if (likely(sched_info_on()))
 		memset(&p->sched_info, 0, sizeof(p->sched_info));
 #endif
-#ifdef CONFIG_SMP
 	p->on_cpu = 0;
-#endif
 	init_task_preempt_count(p);
-#ifdef CONFIG_SMP
 	plist_node_init(&p->pushable_tasks, MAX_PRIO);
 	RB_CLEAR_NODE(&p->pushable_dl_tasks);
-#endif
+
 	return 0;
 }
 
···
 
 	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
 	WRITE_ONCE(p->__state, TASK_RUNNING);
-#ifdef CONFIG_SMP
 	/*
 	 * Fork balancing, do it here and not earlier because:
 	 *  - cpus_ptr can change in the fork path
···
 	p->recent_used_cpu = task_cpu(p);
 	rseq_migrate(p);
 	__set_task_cpu(p, select_task_rq(p, task_cpu(p), &wake_flags));
-#endif
 	rq = __task_rq_lock(p, &rf);
 	update_rq_clock(rq);
 	post_init_entity_util_avg(p);
···
 
 static inline void prepare_task(struct task_struct *next)
 {
-#ifdef CONFIG_SMP
 	/*
 	 * Claim the task as running, we do this before switching to it
 	 * such that any running task will have this set.
···
 	 * its ordering comment.
 	 */
 	WRITE_ONCE(next->on_cpu, 1);
-#endif
 }
 
 static inline void finish_task(struct task_struct *prev)
 {
-#ifdef CONFIG_SMP
 	/*
 	 * This must be the very last reference to @prev from this CPU. After
 	 * p->on_cpu is cleared, the task can be moved to a different CPU. We
···
 	 * Pairs with the smp_cond_load_acquire() in try_to_wake_up().
 	 */
 	smp_store_release(&prev->on_cpu, 0);
-#endif
 }
-
-#ifdef CONFIG_SMP
 
 static void do_balance_callbacks(struct rq *rq, struct balance_callback *head)
 {
···
 		raw_spin_rq_unlock_irqrestore(rq, flags);
 	}
 }
-
-#else /* !CONFIG_SMP: */
-
-static inline void __balance_callbacks(struct rq *rq)
-{
-}
-
-#endif /* !CONFIG_SMP */
 
 static inline void
 prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf)
···
 	struct rq *rq;
 	u64 ns;
 
-#if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
+#ifdef CONFIG_64BIT
 	/*
 	 * 64-bit doesn't need locks to atomically read a 64-bit value.
 	 * So we have a optimization chance when the task's delta_exec is 0.
···
 	if (donor->flags & PF_WQ_WORKER)
 		wq_worker_tick(donor);
 
-#ifdef CONFIG_SMP
 	if (!scx_switched_all()) {
 		rq->idle_balance = idle_cpu(cpu);
 		sched_balance_trigger(rq);
 	}
-#endif
 }
 
 #ifdef CONFIG_NO_HZ_FULL
···
  */
 void __init init_idle(struct task_struct *idle, int cpu)
 {
-#ifdef CONFIG_SMP
 	struct affinity_context ac = (struct affinity_context) {
 		.new_mask  = cpumask_of(cpu),
 		.flags     = 0,
 	};
-#endif
 	struct rq *rq = cpu_rq(cpu);
 	unsigned long flags;
 
···
 	idle->flags |= PF_KTHREAD | PF_NO_SETAFFINITY;
 	kthread_set_per_cpu(idle, cpu);
 
-#ifdef CONFIG_SMP
 	/*
 	 * No validation and serialization required at boot time and for
 	 * setting up the idle tasks of not yet online CPUs.
 	 */
 	set_cpus_allowed_common(idle, &ac);
-#endif
 	/*
 	 * We're having a chicken and egg problem, even though we are
 	 * holding rq->lock, the CPU isn't yet set to this CPU so the
···
 	rq_set_donor(rq, idle);
 	rcu_assign_pointer(rq->curr, idle);
 	idle->on_rq = TASK_ON_RQ_QUEUED;
-#ifdef CONFIG_SMP
 	idle->on_cpu = 1;
-#endif
 	raw_spin_rq_unlock(rq);
 	raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
 
···
 	idle->sched_class = &idle_sched_class;
 	ftrace_graph_init_idle_task(idle, cpu);
 	vtime_init_idle(idle, cpu);
-#ifdef CONFIG_SMP
 	sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
-#endif
 }
-
-#ifdef CONFIG_SMP
 
 int cpuset_cpumask_can_shrink(const struct cpumask *cur,
 			      const struct cpumask *trial)
···
 }
 early_initcall(migration_init);
 
-#else /* !CONFIG_SMP: */
-void __init sched_init_smp(void)
-{
-	sched_init_granularity();
-}
-#endif /* !CONFIG_SMP */
-
 int in_sched_functions(unsigned long addr)
 {
 	return in_lock_functions(addr) ||
···
 	int i;
 
 	/* Make sure the linker didn't screw up */
-#ifdef CONFIG_SMP
 	BUG_ON(!sched_class_above(&stop_sched_class, &dl_sched_class));
-#endif
 	BUG_ON(!sched_class_above(&dl_sched_class, &rt_sched_class));
 	BUG_ON(!sched_class_above(&rt_sched_class, &fair_sched_class));
 	BUG_ON(!sched_class_above(&fair_sched_class, &idle_sched_class));
···
 #endif /* CONFIG_RT_GROUP_SCHED */
 	}
 
-#ifdef CONFIG_SMP
 	init_defrootdomain();
-#endif
 
 #ifdef CONFIG_RT_GROUP_SCHED
 	init_rt_bandwidth(&root_task_group.rt_bandwidth,
···
 		rq->rt.rt_runtime = global_rt_runtime();
 		init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
 #endif
-#ifdef CONFIG_SMP
 		rq->sd = NULL;
 		rq->rd = NULL;
 		rq->cpu_capacity = SCHED_CAPACITY_SCALE;
···
 		INIT_LIST_HEAD(&rq->cfs_tasks);
 
 		rq_attach_root(rq, &def_root_domain);
-# ifdef CONFIG_NO_HZ_COMMON
+#ifdef CONFIG_NO_HZ_COMMON
 		rq->last_blocked_load_update_tick = jiffies;
 		atomic_set(&rq->nohz_flags, 0);
 
 		INIT_CSD(&rq->nohz_csd, nohz_csd_func, rq);
-# endif
-# ifdef CONFIG_HOTPLUG_CPU
+#endif
+#ifdef CONFIG_HOTPLUG_CPU
 		rcuwait_init(&rq->hotplug_wait);
-# endif
-#endif /* CONFIG_SMP */
+#endif
 		hrtick_rq_init(rq);
 		atomic_set(&rq->nr_iowait, 0);
 		fair_server_init(rq);
···
 
 #ifdef CONFIG_SMP
 	idle_thread_set_boot_cpu();
-	balance_push_set(smp_processor_id(), false);
 #endif
+
+	balance_push_set(smp_processor_id(), false);
 	init_sched_fair_class();
 	init_sched_ext_class();
 

kernel/sched/cpudeadline.h

···
 	struct cpudl_item	*elements;
 };
 
-#ifdef CONFIG_SMP
 int  cpudl_find(struct cpudl *cp, struct task_struct *p, struct cpumask *later_mask);
 void cpudl_set(struct cpudl *cp, int cpu, u64 dl);
 void cpudl_clear(struct cpudl *cp, int cpu);
···
 void cpudl_set_freecpu(struct cpudl *cp, int cpu);
 void cpudl_clear_freecpu(struct cpudl *cp, int cpu);
 void cpudl_cleanup(struct cpudl *cp);
-#endif /* CONFIG_SMP */

kernel/sched/cpupri.h

···
 	int			*cpu_to_pri;
 };
 
-#ifdef CONFIG_SMP
 int  cpupri_find(struct cpupri *cp, struct task_struct *p,
 		 struct cpumask *lowest_mask);
 int  cpupri_find_fitness(struct cpupri *cp, struct task_struct *p,
···
 void cpupri_set(struct cpupri *cp, int cpu, int pri);
 int  cpupri_init(struct cpupri *cp);
 void cpupri_cleanup(struct cpupri *cp);
-#endif /* CONFIG_SMP */

kernel/sched/deadline.c

···
 }
 #endif /* !CONFIG_RT_MUTEXES */
 
-#ifdef CONFIG_SMP
 static inline struct dl_bw *dl_bw_of(int i)
 {
 	RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
···
 		rq->dl.extra_bw += bw;
 	}
 }
-#else /* !CONFIG_SMP: */
-static inline struct dl_bw *dl_bw_of(int i)
-{
-	return &cpu_rq(i)->dl.dl_bw;
-}
-
-static inline int dl_bw_cpus(int i)
-{
-	return 1;
-}
-
-static inline unsigned long dl_bw_capacity(int i)
-{
-	return SCHED_CAPACITY_SCALE;
-}
-
-bool dl_bw_visited(int cpu, u64 cookie)
-{
-	return false;
-}
-
-static inline
-void __dl_update(struct dl_bw *dl_b, s64 bw)
-{
-	struct dl_rq *dl = container_of(dl_b, struct dl_rq, dl_bw);
-
-	dl->extra_bw += bw;
-}
-#endif /* !CONFIG_SMP */
 
 static inline
 void __dl_sub(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
···
 {
 	dl_rq->root = RB_ROOT_CACHED;
 
-#ifdef CONFIG_SMP
 	/* zero means no -deadline tasks */
 	dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0;
 
 	dl_rq->overloaded = 0;
 	dl_rq->pushable_dl_tasks_root = RB_ROOT_CACHED;
-#else
-	init_dl_bw(&dl_rq->dl_bw);
-#endif
 
 	dl_rq->running_bw = 0;
 	dl_rq->this_bw = 0;
 	init_dl_rq_bw_ratio(dl_rq);
 }
-
-#ifdef CONFIG_SMP
 
 static inline int dl_overloaded(struct rq *rq)
 {
···
 
 	return later_rq;
 }
-
-#else /* !CONFIG_SMP: */
-
-static inline
-void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
-{
-}
-
-static inline
-void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
-{
-}
-
-static inline
-void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
-{
-}
-
-static inline
-void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
-{
-}
-
-static inline void deadline_queue_push_tasks(struct rq *rq)
-{
-}
-
-static inline void deadline_queue_pull_task(struct rq *rq)
-{
-}
-#endif /* !CONFIG_SMP */
 
 static void
 enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags);
···
 
 static void __push_dl_task(struct rq *rq, struct rq_flags *rf)
 {
-#ifdef CONFIG_SMP
 	/*
 	 * Queueing this task back might have overloaded rq, check if we need
 	 * to kick someone away.
···
 		push_dl_task(rq);
 		rq_repin_lock(rq, rf);
 	}
-#endif /* CONFIG_SMP */
 }
 
 /* a defer timer will not be reset if the runtime consumed was < dl_server_min_res */
···
 		goto unlock;
 	}
 
-#ifdef CONFIG_SMP
 	if (unlikely(!rq->online)) {
 		/*
 		 * If the runqueue is no longer available, migrate the
···
 		 * there.
 		 */
 	}
-#endif /* CONFIG_SMP */
 
 	enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
 	if (dl_task(rq->donor))
···
 #define __node_2_dle(node) \
 	rb_entry((node), struct sched_dl_entity, rb_node)
 
-#ifdef CONFIG_SMP
-
 static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
 {
 	struct rq *rq = rq_of_dl_rq(dl_rq);
···
 		cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline);
 	}
 }
-
-#else /* !CONFIG_SMP: */
-
-static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
-static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
-
-#endif /* !CONFIG_SMP */
 
 static inline
 void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
···
 	rq_clock_skip_update(rq);
 }
 
-#ifdef CONFIG_SMP
-
 static inline bool dl_task_is_earliest_deadline(struct task_struct *p,
 						 struct rq *rq)
 {
···
 
 	return sched_stop_runnable(rq) || sched_dl_runnable(rq);
 }
-#endif /* CONFIG_SMP */
 
 /*
  * Only called when both the current and waking task are -deadline
···
 		return;
 	}
 
-#ifdef CONFIG_SMP
 	/*
 	 * In the unlikely case current and p have the same deadline
 	 * let us try to decide what's the best thing to do...
···
 	if ((p->dl.deadline == rq->donor->dl.deadline) &&
 	    !test_tsk_need_resched(rq->curr))
 		check_preempt_equal_dl(rq, p);
-#endif /* CONFIG_SMP */
 }
 
 #ifdef CONFIG_SCHED_HRTICK
···
 	 * sched_fork()
 	 */
 }
-
-#ifdef CONFIG_SMP
 
 /* Only try algorithms three times */
 #define DL_MAX_TRIES 3
···
 	dl_clear_root_domain(cpu_rq(cpu)->rd);
 }
 
-#endif /* CONFIG_SMP */
-
 static void switched_from_dl(struct rq *rq, struct task_struct *p)
 {
 	/*
···
 	}
 
 	if (rq->donor != p) {
-#ifdef CONFIG_SMP
 		if (p->nr_cpus_allowed > 1 && rq->dl.overloaded)
 			deadline_queue_push_tasks(rq);
-#endif
 		if (dl_task(rq->donor))
 			wakeup_preempt_dl(rq, p, 0);
 		else
···
 	.put_prev_task		= put_prev_task_dl,
 	.set_next_task		= set_next_task_dl,
 
-#ifdef CONFIG_SMP
 	.balance		= balance_dl,
 	.select_task_rq		= select_task_rq_dl,
 	.migrate_task_rq	= migrate_task_rq_dl,
···
 	.rq_offline             = rq_offline_dl,
 	.task_woken		= task_woken_dl,
 	.find_lock_rq		= find_lock_later_rq,
-#endif /* CONFIG_SMP */
 
 	.task_tick		= task_tick_dl,
 	.task_fork              = task_fork_dl,
···
 	return false;
 }
 
-#ifdef CONFIG_SMP
 int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,
 				 const struct cpumask *trial)
 {
···
 {
 	dl_bw_manage(dl_bw_req_free, cpu, dl_bw);
 }
-#endif /* CONFIG_SMP */
 
 void print_dl_stats(struct seq_file *m, int cpu)
 {

kernel/sched/debug.c

···
 
 __read_mostly bool sched_debug_verbose;
 
-#ifdef CONFIG_SMP
 static struct dentry           *sd_dentry;
 
 
···
 
 	return result;
 }
-#else /* !CONFIG_SMP: */
-# define sched_verbose_write debugfs_write_file_bool
-#endif /* !CONFIG_SMP */
 
 static const struct file_operations sched_verbose_fops = {
 	.read =         debugfs_read_file_bool,
···
 }
 late_initcall(sched_init_debug);
 
-#ifdef CONFIG_SMP
-
 static cpumask_var_t		sd_sysctl_cpus;
 
 static int sd_flags_show(struct seq_file *m, void *v)
···
 	if (cpumask_available(sd_sysctl_cpus))
 		__cpumask_set_cpu(cpu, sd_sysctl_cpus);
 }
-
-#endif /* CONFIG_SMP */
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
 static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group *tg)
···
 	SEQ_printf(m, "  .%-30s: %lu\n", #x, (unsigned long)(dl_rq->x))
 
 	PU(dl_nr_running);
-#ifdef CONFIG_SMP
 	dl_bw = &cpu_rq(cpu)->rd->dl_bw;
-#else
-	dl_bw = &dl_rq->dl_bw;
-#endif
 	SEQ_printf(m, "  .%-30s: %lld\n", "dl_bw->bw", dl_bw->bw);
 	SEQ_printf(m, "  .%-30s: %lld\n", "dl_bw->total_bw", dl_bw->total_bw);
 

kernel/sched/fair.c

···
 }
 __setup("sched_thermal_decay_shift=", setup_sched_thermal_decay_shift);
 
-#ifdef CONFIG_SMP
 /*
  * For asym packing, by default the lower numbered CPU has higher priority.
  */
···
  * (default: ~5%)
  */
 #define capacity_greater(cap1, cap2) ((cap1) * 1024 > (cap2) * 1078)
-#endif /* CONFIG_SMP */
 
 #ifdef CONFIG_CFS_BANDWIDTH
 /*
···
 /**************************************************************
  * Scheduling class statistics methods:
  */
-#ifdef CONFIG_SMP
 int sched_update_scaling(void)
 {
 	unsigned int factor = get_update_sysctl_factor();
···
 
 	return 0;
 }
-#endif /* CONFIG_SMP */
 
 static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se);
 
···
 }
 
 #include "pelt.h"
-
-#ifdef CONFIG_SMP
 
 static int select_idle_sibling(struct task_struct *p, int prev_cpu, int cpu);
 static unsigned long task_h_load(struct task_struct *p);
···
 
 	sa->runnable_avg = sa->util_avg;
 }
-
-#else /* !CONFIG_SMP: */
-void init_entity_runnable_average(struct sched_entity *se)
-{
-}
-void post_init_entity_util_avg(struct task_struct *p)
-{
-}
-static void update_tg_load_avg(struct cfs_rq *cfs_rq)
-{
-}
-#endif /* !CONFIG_SMP */
 
 static s64 update_curr_se(struct rq *rq, struct sched_entity *curr)
 {
···
 account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
 	update_load_add(&cfs_rq->load, se->load.weight);
-#ifdef CONFIG_SMP
 	if (entity_is_task(se)) {
 		struct rq *rq = rq_of(cfs_rq);
 
 		account_numa_enqueue(rq, task_of(se));
 		list_add(&se->group_node, &rq->cfs_tasks);
 	}
-#endif
 	cfs_rq->nr_queued++;
 }
 
···
 account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
 	update_load_sub(&cfs_rq->load, se->load.weight);
-#ifdef CONFIG_SMP
 	if (entity_is_task(se)) {
 		account_numa_dequeue(rq_of(cfs_rq), task_of(se));
 		list_del_init(&se->group_node);
 	}
-#endif
 	cfs_rq->nr_queued--;
 }
 
···
 	*ptr -= min_t(typeof(*ptr), *ptr, _val);		\
 } while (0)
 
-#ifdef CONFIG_SMP
 static inline void
 enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
···
 	cfs_rq->avg.load_sum = max_t(u32, cfs_rq->avg.load_sum,
 					  cfs_rq->avg.load_avg * PELT_MIN_DIVIDER);
 }
-#else /* !CONFIG_SMP: */
-static inline void
-enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
-static inline void
-dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
-#endif /* !CONFIG_SMP */
 
 static void place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags);
 
···
 
 	update_load_set(&se->load, weight);
 
-#ifdef CONFIG_SMP
 	do {
 		u32 divider = get_pelt_divider(&se->avg);
 
 		se->avg.load_avg = div_u64(se_weight(se) * se->avg.load_sum, divider);
 	} while (0);
-#endif
 
 	enqueue_load_avg(cfs_rq, se);
 	if (se->on_rq) {
···
 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
-#ifdef CONFIG_SMP
 /*
  * All this does is approximate the hierarchical proportion which includes that
  * global sum we all love to hate.
···
 	 */
 	return clamp_t(long, shares, MIN_SHARES, tg_shares);
 }
-#endif /* CONFIG_SMP */
 
 /*
  * Recomputes the group entity based on the current state of its group
···
 	if (throttled_hierarchy(gcfs_rq))
 		return;
 
-#ifndef CONFIG_SMP
-	shares = READ_ONCE(gcfs_rq->tg->shares);
-#else
 	shares = calc_group_shares(gcfs_rq);
-#endif
 	if (unlikely(se->load.weight != shares))
 		reweight_entity(cfs_rq_of(se), se, shares);
 }
···
 	}
 }
 
-#ifdef CONFIG_SMP
 static inline bool load_avg_is_decayed(struct sched_avg *sa)
 {
 	if (sa->load_sum)
···
 	rq->misfit_task_load = max_t(unsigned long, task_h_load(p), 1);
 }
 
-#else /* !CONFIG_SMP: */
-
-static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
-{
-	return !cfs_rq->nr_queued;
-}
-
-#define UPDATE_TG	0x0
-#define SKIP_AGE_LOAD	0x0
-#define DO_ATTACH	0x0
-#define DO_DETACH	0x0
-
-static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int not_used1)
-{
-	cfs_rq_util_change(cfs_rq, 0);
-}
-
-static inline void remove_entity_load_avg(struct sched_entity *se) {}
-
-static inline void
-attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
-static inline void
-detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
-
-static inline int sched_balance_newidle(struct rq *rq, struct rq_flags *rf)
-{
-	return 0;
-}
-
-static inline void
-util_est_enqueue(struct cfs_rq *cfs_rq, struct task_struct *p) {}
-
-static inline void
-util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p) {}
-
-static inline void
-util_est_update(struct cfs_rq *cfs_rq, struct task_struct *p,
-		bool task_sleep) {}
-static inline void update_misfit_status(struct task_struct *p, struct rq *rq) {}
-
-#endif /* !CONFIG_SMP */
-
 void __setparam_fair(struct task_struct *p, const struct sched_attr *attr)
 {
 	struct sched_entity *se = &p->se;
···
 		resched_curr(rq);
 }
 
-#ifdef CONFIG_SMP
 static void __cfsb_csd_unthrottle(void *arg)
 {
 	struct cfs_rq *cursor, *tmp;
···
 	if (first)
 		smp_call_function_single_async(cpu_of(rq), &rq->cfsb_csd);
 }
-#else /* !CONFIG_SMP: */
-static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
-{
-	unthrottle_cfs_rq(cfs_rq);
-}
-#endif /* !CONFIG_SMP */
 
 static void unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
 {
···
 	 * guaranteed at this point that no additional cfs_rq of this group can
 	 * join a CSD list.
 	 */
-#ifdef CONFIG_SMP
 	for_each_possible_cpu(i) {
 		struct rq *rq = cpu_rq(i);
 		unsigned long flags;
···
 		__cfsb_csd_unthrottle(rq);
 		local_irq_restore(flags);
 	}
-#endif
 }
 
 /*
···
 }
 #endif /* !CONFIG_SCHED_HRTICK */
 
-#ifdef CONFIG_SMP
 static inline bool cpu_overutilized(int cpu)
 {
 	unsigned long  rq_util_min, rq_util_max;
···
 	if (!is_rd_overutilized(rq->rd) && cpu_overutilized(rq->cpu))
 		set_rd_overutilized(rq->rd, 1);
 }
-#else /* !CONFIG_SMP: */
-static inline void check_update_overutilized_status(struct rq *rq) { }
-#endif /* !CONFIG_SMP */
 
 /* Runqueue only has SCHED_IDLE tasks enqueued */
 static int sched_idle_rq(struct rq *rq)
···
 			rq->nr_running);
 }
 
-#ifdef CONFIG_SMP
 static int sched_idle_cpu(int cpu)
 {
 	return sched_idle_rq(cpu_rq(cpu));
 }
-#endif
 
 static void
 requeue_delayed_entity(struct sched_entity *se)
···
 {
 	return (rq->cfs.h_nr_queued - rq->cfs.h_nr_runnable);
 }
-
-#ifdef CONFIG_SMP
 
 /* Working cpumask for: sched_balance_rq(), sched_balance_newidle(). */
 static DEFINE_PER_CPU(cpumask_var_t, load_balance_mask);
···
 
 	return sched_balance_newidle(rq, rf) != 0;
 }
-#else /* !CONFIG_SMP: */
-static inline void set_task_max_allowed_capacity(struct task_struct *p) {}
-#endif /* !CONFIG_SMP */
 
 static void set_next_buddy(struct sched_entity *se)
 {
···
 	return true;
 }
 
-#ifdef CONFIG_SMP
 /**************************************************
  * Fair scheduling class load-balancing methods.
  *
···
 	clear_tg_offline_cfs_rqs(rq);
 }
 
-#endif /* CONFIG_SMP */
-
 #ifdef CONFIG_SCHED_CORE
 static inline bool
 __entity_slice_used(struct sched_entity *se, int min_nr_tasks)
···
 {
 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
 
-#ifdef CONFIG_SMP
 	/*
 	 * In case the task sched_avg hasn't been attached:
 	 * - A forked task which hasn't been woken up by wake_up_new_task().
···
 	 */
 	if (!se->avg.last_update_time)
 		return;
-#endif
 
 	/* Catch up with the cfs_rq and remove our load when we leave */
 	update_load_avg(cfs_rq, se, 0);
···
 {
 	struct sched_entity *se = &p->se;
 
-#ifdef CONFIG_SMP
 	if (task_on_rq_queued(p)) {
 		/*
 		 * Move the next running task to the front of the list, so our
···
 		 */
 		list_move(&se->group_node, &rq->cfs_tasks);
 	}
-#endif
 	if (!first)
 		return;
 
···
 {
 	cfs_rq->tasks_timeline = RB_ROOT_CACHED;
 	cfs_rq->min_vruntime = (u64)(-(1LL << 20));
-#ifdef CONFIG_SMP
 	raw_spin_lock_init(&cfs_rq->removed.lock);
-#endif
 }
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
···
 
 	detach_task_cfs_rq(p);
 
-#ifdef CONFIG_SMP
 	/* Tell se's cfs_rq has been changed -- migrated */
 	p->se.avg.last_update_time = 0;
-#endif
 	set_task_rq(p, task_cpu(p));
 	attach_task_cfs_rq(p);
 }
···
 	.put_prev_task		= put_prev_task_fair,
 	.set_next_task          = set_next_task_fair,
 
-#ifdef CONFIG_SMP
 	.balance		= balance_fair,
 	.select_task_rq		= select_task_rq_fair,
 	.migrate_task_rq	= migrate_task_rq_fair,
···
 
 	.task_dead		= task_dead_fair,
 	.set_cpus_allowed	= set_cpus_allowed_fair,
-#endif
 
 	.task_tick		= task_tick_fair,
 	.task_fork		= task_fork_fair,
···
 
 __init void init_sched_fair_class(void)
 {
-#ifdef CONFIG_SMP
 	int i;
 
 	for_each_possible_cpu(i) {
···
 	nohz.next_blocked = jiffies;
 	zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
 #endif
-#endif /* CONFIG_SMP */
 }

kernel/sched/pelt.h

···
 #define _KERNEL_SCHED_PELT_H
 #include "sched.h"
 
-#ifdef CONFIG_SMP
 #include "sched-pelt.h"
 
 int __update_load_avg_blocked_se(u64 now, struct sched_entity *se);
···
 	return rq_clock_pelt(rq_of(cfs_rq));
 }
 #endif /* !CONFIG_CFS_BANDWIDTH */
-
-#else /* !CONFIG_SMP: */
-
-static inline int
-update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
-{
-	return 0;
-}
-
-static inline int
-update_rt_rq_load_avg(u64 now, struct rq *rq, int running)
-{
-	return 0;
-}
-
-static inline int
-update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
-{
-	return 0;
-}
-
-static inline int
-update_hw_load_avg(u64 now, struct rq *rq, u64 capacity)
-{
-	return 0;
-}
-
-static inline u64 hw_load_avg(struct rq *rq)
-{
-	return 0;
-}
-
-static inline int
-update_irq_load_avg(struct rq *rq, u64 running)
-{
-	return 0;
-}
-
-static inline u64 rq_clock_pelt(struct rq *rq)
-{
-	return rq_clock_task(rq);
-}
-
-static inline void
-update_rq_clock_pelt(struct rq *rq, s64 delta) { }
-
-static inline void
-update_idle_rq_clock_pelt(struct rq *rq) { }
-
-static inline void update_idle_cfs_rq_clock_pelt(struct cfs_rq *cfs_rq) { }
-#endif /* !CONFIG_SMP */
 
 #endif /* _KERNEL_SCHED_PELT_H */

kernel/sched/rt.c

···
 					GFP_KERNEL, cpu_to_node(i));
 	}
 }
-#endif /* CONFIG_SMP */
+#else /* !CONFIG_SMP: */
+void __init init_sched_rt_class(void)
+{
+}
+#endif /* !CONFIG_SMP */
 
 /*
  * When switching a task to RT, we may overload the runqueue

kernel/sched/sched.h

···
 	/* runqueue "owned" by this group on each CPU */
 	struct cfs_rq		**cfs_rq;
 	unsigned long		shares;
-#ifdef CONFIG_SMP
 	/*
 	 * load_avg can be heavily contended at clock tick time, so put
 	 * it in its own cache-line separated from the fields above which
 	 * will also be accessed at each tick.
 	 */
 	atomic_long_t		load_avg ____cacheline_aligned;
-#endif /* CONFIG_SMP */
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 
 #ifdef CONFIG_RT_GROUP_SCHED
···
 
 extern int sched_group_set_idle(struct task_group *tg, long idle);
 
-#ifdef CONFIG_SMP
 extern void set_task_rq_fair(struct sched_entity *se,
 			     struct cfs_rq *prev, struct cfs_rq *next);
-#else /* !CONFIG_SMP: */
-static inline void set_task_rq_fair(struct sched_entity *se,
-			     struct cfs_rq *prev, struct cfs_rq *next) { }
-#endif /* !CONFIG_SMP */
 #else /* !CONFIG_FAIR_GROUP_SCHED: */
 static inline int sched_group_set_shares(struct task_group *tg, unsigned long shares) { return 0; }
 static inline int sched_group_set_idle(struct task_group *tg, long idle) { return 0; }
···
 	struct sched_entity	*curr;
 	struct sched_entity	*next;
 
-#ifdef CONFIG_SMP
 	/*
 	 * CFS load tracking
 	 */
···
 	u64			last_h_load_update;
 	struct sched_entity	*h_load_next;
 #endif /* CONFIG_FAIR_GROUP_SCHED */
-#endif /* CONFIG_SMP */
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
 	struct rq		*rq;	/* CPU runqueue to which this cfs_rq is attached */
···
 	struct rt_prio_array	active;
 	unsigned int		rt_nr_running;
 	unsigned int		rr_nr_running;
-#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
 	struct {
 		int		curr; /* highest queued rt task prio */
-#ifdef CONFIG_SMP
 		int		next; /* next highest */
-#endif
 	} highest_prio;
-#endif
 #ifdef CONFIG_SMP
 	bool			overloaded;
 	struct plist_head	pushable_tasks;
···
 
 	unsigned int		dl_nr_running;
 
-#ifdef CONFIG_SMP
 	/*
 	 * Deadline values of the currently executing and the
 	 * earliest ready task on this rq. Caching these facilitates
···
 	 * of the leftmost (earliest deadline) element.
 	 */
 	struct rb_root_cached	pushable_dl_tasks_root;
-#else /* !CONFIG_SMP: */
-	struct dl_bw		dl_bw;
-#endif /* !CONFIG_SMP */
+
 	/*
 	 * "Active utilization" for this runqueue: increased when a
 	 * task wakes up (becomes TASK_RUNNING) and decreased when a
···
 
 #endif /* !CONFIG_FAIR_GROUP_SCHED */
 
-#ifdef CONFIG_SMP
 /*
  * XXX we want to get rid of these helpers and use the full load resolution.
  */
···
 #ifdef HAVE_RT_PUSH_IPI
 extern void rto_push_irq_work_func(struct irq_work *work);
 #endif
-#endif /* CONFIG_SMP */
 
 #ifdef CONFIG_UCLAMP_TASK
 /*
···
 	unsigned int		numa_migrate_on;
 #endif
 #ifdef CONFIG_NO_HZ_COMMON
-#ifdef CONFIG_SMP
 	unsigned long		last_blocked_load_update_tick;
 	unsigned int		has_blocked_load;
 	call_single_data_t	nohz_csd;
-#endif /* CONFIG_SMP */
 	unsigned int		nohz_tick_stopped;
 	atomic_t		nohz_flags;
 #endif /* CONFIG_NO_HZ_COMMON */
 
-#ifdef CONFIG_SMP
 	unsigned int		ttwu_pending;
-#endif
 	u64			nr_switches;
 
 #ifdef CONFIG_UCLAMP_TASK
···
 	int membarrier_state;
 #endif
 
-#ifdef CONFIG_SMP
 	struct root_domain		*rd;
 	struct sched_domain __rcu	*sd;
 
···
 #ifdef CONFIG_HOTPLUG_CPU
 	struct rcuwait		hotplug_wait;
 #endif
-#endif /* CONFIG_SMP */
 
 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
 	u64			prev_irq_time;
···
 	struct cpuidle_state	*idle_state;
 #endif
 
-#ifdef CONFIG_SMP
 	unsigned int		nr_pinned;
-#endif
 	unsigned int		push_busy;
 	struct cpu_stop_work	push_work;
 
···
 	/* Scratch cpumask to be temporarily used under rq_lock */
 	cpumask_var_t		scratch_mask;
 
-#if defined(CONFIG_CFS_BANDWIDTH) && defined(CONFIG_SMP)
+#ifdef CONFIG_CFS_BANDWIDTH
 	call_single_data_t	cfsb_csd;
 	struct list_head	cfsb_csd_list;
 #endif
···
 
 #endif /* !CONFIG_NUMA_BALANCING */
 
-#ifdef CONFIG_SMP
-
 static inline void
 queue_balance_callback(struct rq *rq,
 		       struct balance_callback *head,
···
 		return cpu_possible_mask; /* &init_task.cpus_mask */
 	return p->user_cpus_ptr;
 }
-
-#endif /* CONFIG_SMP */
 
 #ifdef CONFIG_CGROUP_SCHED
 
···
 	void (*put_prev_task)(struct rq *rq, struct task_struct *p, struct task_struct *next);
 	void (*set_next_task)(struct rq *rq, struct task_struct *p, bool first);
 
-#ifdef CONFIG_SMP
 	int  (*select_task_rq)(struct task_struct *p, int task_cpu, int flags);
 
 	void (*migrate_task_rq)(struct task_struct *p, int new_cpu);
···
 	void (*rq_offline)(struct rq *rq);
 
 	struct rq *(*find_lock_rq)(struct task_struct *p, struct rq *rq);
-#endif /* CONFIG_SMP */
 
 	void (*task_tick)(struct rq *rq, struct task_struct *p, int queued);
 	void (*task_fork)(struct task_struct *p);
···
 #define SCA_MIGRATE_ENABLE	0x04
 #define SCA_USER		0x08
 
-#ifdef CONFIG_SMP
-
 extern void update_group_capacity(struct sched_domain *sd, int cpu);
 
 extern void sched_balance_trigger(struct rq *rq);
···
 }
 
 extern int push_cpu_stop(void *arg);
-
-#else /* !CONFIG_SMP: */
-
-static inline bool task_allowed_on_cpu(struct task_struct *p, int cpu)
-{
-	return true;
-}
-
-static inline int __set_cpus_allowed_ptr(struct task_struct *p,
-					 struct affinity_context *ctx)
-{
-	return set_cpus_allowed_ptr(p, ctx->new_mask);
-}
-
-static inline cpumask_t *alloc_user_cpus_ptr(int node)
-{
-	return NULL;
-}
-
-#endif /* !CONFIG_SMP */
 
 #ifdef CONFIG_CPU_IDLE
 
···
 { class_##name##_t _t = { .lock = lock, .lock2 = lock2 }, *_T = &_t;			\
   _lock; return _t; }
 
-#ifdef CONFIG_SMP
-
 static inline bool rq_order_less(struct rq *rq1, struct rq *rq2)
 {
 #ifdef CONFIG_SCHED_CORE
···
 
 extern bool sched_smp_initialized;
 
-#else /* !CONFIG_SMP: */
-
-/*
- * double_rq_lock - safely lock two runqueues
- *
- * Note this does not disable interrupts like task_rq_lock,
- * you need to do so manually before calling.
- */
-static inline void double_rq_lock(struct rq *rq1, struct rq *rq2)
-	__acquires(rq1->lock)
-	__acquires(rq2->lock)
-{
-	WARN_ON_ONCE(!irqs_disabled());
-	WARN_ON_ONCE(rq1 != rq2);
-	raw_spin_rq_lock(rq1);
-	__acquire(rq2->lock);	/* Fake it out ;) */
-	double_rq_clock_clear_update(rq1, rq2);
-}
-
-/*
- * double_rq_unlock - safely unlock two runqueues
- *
- * Note this does not restore interrupts like task_rq_unlock,
- * you need to do so manually after calling.
- */
-static inline void double_rq_unlock(struct rq *rq1, struct rq *rq2)
-	__releases(rq1->lock)
-	__releases(rq2->lock)
-{
-	WARN_ON_ONCE(rq1 != rq2);
-	raw_spin_rq_unlock(rq1);
-	__release(rq2->lock);
-}
-
-#endif /* !CONFIG_SMP */
-
 DEFINE_LOCK_GUARD_2(double_rq_lock, struct rq,
 		    double_rq_lock(_T->lock, _T->lock2),
 		    double_rq_unlock(_T->lock, _T->lock2))
···
 static inline void nohz_balance_exit_idle(struct rq *rq) { }
 #endif /* !CONFIG_NO_HZ_COMMON */
 
-#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
+#ifdef CONFIG_NO_HZ_COMMON
 extern void nohz_run_idle_balance(int cpu);
 #else
 static inline void nohz_run_idle_balance(int cpu) { }
···
 # define arch_scale_freq_invariant()	false
 #endif
 
-#ifdef CONFIG_SMP
-
 unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
 				 unsigned long *min,
 				 unsigned long *max);
···
 {
 	return READ_ONCE(rq->avg_rt.util_avg);
 }
-
-#else /* !CONFIG_SMP: */
-static inline bool update_other_load_avgs(struct rq *rq) { return false; }
-#endif /* !CONFIG_SMP */
 
 #ifdef CONFIG_UCLAMP_TASK
 
···
 
 #endif /* !CONFIG_MEMBARRIER */
 
-#ifdef CONFIG_SMP
 static inline bool is_per_cpu_kthread(struct task_struct *p)
 {
 	if (!(p->flags & PF_KTHREAD))
···
 
 	return true;
 }
-#endif /* CONFIG_SMP */
 
 extern void swake_up_all_locked(struct swait_queue_head *q);
 extern void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait);
···
 
 extern u64 avg_vruntime(struct cfs_rq *cfs_rq);
 extern int entity_eligible(struct cfs_rq *cfs_rq, struct sched_entity *se);
-#ifdef CONFIG_SMP
 static inline
 void move_queued_task_locked(struct rq *src_rq, struct rq *dst_rq, struct task_struct *task)
 {
···
 
 	return false;
 }
-#endif /* CONFIG_SMP */
 
 #ifdef CONFIG_RT_MUTEXES
 
···
 				const struct sched_class *prev_class,
 				int oldprio);
 
-#ifdef CONFIG_SMP
 extern struct balance_callback *splice_balance_callbacks(struct rq *rq);
 extern void balance_callbacks(struct rq *rq, struct balance_callback *head);
-#else /* !CONFIG_SMP: */
-
-static inline struct balance_callback *splice_balance_callbacks(struct rq *rq)
-{
-	return NULL;
-}
-
-static inline void balance_callbacks(struct rq *rq, struct balance_callback *head)
-{
-}
-
-#endif /* !CONFIG_SMP */
 
 #ifdef CONFIG_SCHED_CLASS_EXT
 /*

kernel/sched/syscalls.c

···
 	return copy_struct_to_user(uattr, usize, &kattr, sizeof(kattr), NULL);
 }
 
-#ifdef CONFIG_SMP
 int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask)
 {
 	/*
···
 
 	return 0;
 }
-#endif /* CONFIG_SMP */
 
 int __sched_setaffinity(struct task_struct *p, struct affinity_context *ctx)
 {

kernel/sched/topology.c

···
 	mutex_unlock(&sched_domains_mutex);
 }
 
-#ifdef CONFIG_SMP
-
 /* Protected by sched_domains_mutex: */
 static cpumask_var_t sched_domains_tmpmask;
 static cpumask_var_t sched_domains_tmpmask2;
···
 	update_group_capacity(sd, cpu);
 }
 
-#ifdef CONFIG_SMP
-
 /* Update the "asym_prefer_cpu" when arch_asym_cpu_priority() changes. */
 void sched_update_asym_prefer_cpu(int cpu, int old_prio, int new_prio)
 {
+#ifdef CONFIG_SMP
 	int asym_prefer_cpu = cpu;
 	struct sched_domain *sd;
 
···
 
 		WRITE_ONCE(sg->asym_prefer_cpu, asym_prefer_cpu);
 	}
-}
-
 #endif /* CONFIG_SMP */
+}
 
 /*
  * Set of available CPUs grouped by their corresponding capacities
···
 	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
 	sched_domains_mutex_unlock();
 }
-
-#endif /* CONFIG_SMP */