sched/idle: Merge kernel/sched/idle.c and kernel/sched/idle_task.c

Merge these two small .c modules as they implement two aspects
of idle task handling.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 125 insertions, 120 deletions

diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile
index e2f9d4feff40..d9a02b318108 100644
--- a/kernel/sched/Makefile
+++ b/kernel/sched/Makefile
@@ -17,8 +17,9 @@ CFLAGS_core.o := $(PROFILING) -fno-omit-frame-pointer
 endif
 
 obj-y += core.o loadavg.o clock.o cputime.o
-obj-y += idle_task.o fair.o rt.o deadline.o
-obj-y += wait.o wait_bit.o swait.o completion.o idle.o
+obj-y += idle.o fair.o rt.o deadline.o
+obj-y += wait.o wait_bit.o swait.o completion.o
+
 obj-$(CONFIG_SMP) += cpupri.o cpudeadline.o topology.o stop_task.o
 obj-$(CONFIG_SCHED_AUTOGROUP) += autogroup.o
 obj-$(CONFIG_SCHEDSTATS) += stats.o
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 2760e0357271..2975f195e1c4 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -1,5 +1,9 @@
 /*
- * Generic entry points for the idle threads
+ * 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 )
  */
 #include "sched.h"
 
@@ -33,6 +37,7 @@ void cpu_idle_poll_ctrl(bool enable)
 static int __init cpu_idle_poll_setup(char *__unused)
 {
         cpu_idle_force_poll = 1;
+
         return 1;
 }
 __setup("nohlt", cpu_idle_poll_setup);
@@ -40,6 +45,7 @@ __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);
@@ -51,12 +57,14 @@ static noinline int __cpuidle cpu_idle_poll(void)
         trace_cpu_idle_rcuidle(0, smp_processor_id());
         local_irq_enable();
         stop_critical_timings();
+
         while (!tif_need_resched() &&
                 (cpu_idle_force_poll || tick_check_broadcast_expired()))
                 cpu_relax();
         start_critical_timings();
         trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
         rcu_idle_exit();
+
         return 1;
 }
 
@@ -337,3 +345,116 @@ void cpu_startup_entry(enum cpuhp_state 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 sd_flag, int flags)
+{
+        return task_cpu(p); /* IDLE tasks as never migrated */
+}
+#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 struct task_struct *
+pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+{
+        put_prev_task(rq, prev);
+        update_idle_core(rq);
+        schedstat_inc(rq->sched_goidle);
+
+        return rq->idle;
+}
+
+/*
+ * 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_unlock_irq(&rq->lock);
+        printk(KERN_ERR "bad: scheduling from the idle thread!\n");
+        dump_stack();
+        raw_spin_lock_irq(&rq->lock);
+}
+
+static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
+{
+}
+
+/*
+ * 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 set_curr_task_idle(struct rq *rq)
+{
+}
+
+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 unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
+{
+        return 0;
+}
+
+static void update_curr_idle(struct rq *rq)
+{
+}
+
+/*
+ * Simple, special scheduling class for the per-CPU idle tasks:
+ */
+const struct sched_class idle_sched_class = {
+        /* .next is NULL */
+        /* 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,
+
+#ifdef CONFIG_SMP
+        .select_task_rq         = select_task_rq_idle,
+        .set_cpus_allowed       = set_cpus_allowed_common,
+#endif
+
+        .set_curr_task          = set_curr_task_idle,
+        .task_tick              = task_tick_idle,
+
+        .get_rr_interval        = get_rr_interval_idle,
+
+        .prio_changed           = prio_changed_idle,
+        .switched_to            = switched_to_idle,
+        .update_curr            = update_curr_idle,
+};
diff --git a/kernel/sched/idle_task.c b/kernel/sched/idle_task.c
deleted file mode 100644
index 488222ac4651..000000000000
--- a/kernel/sched/idle_task.c
+++ /dev/null
@@ -1,117 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * idle-task scheduling class.
- *
- * (NOTE: these are not related to SCHED_IDLE batch scheduling tasks which are
- *  handled in sched/fair.c)
- */
-#include "sched.h"
-
-#ifdef CONFIG_SMP
-static int
-select_task_rq_idle(struct task_struct *p, int cpu, int sd_flag, int flags)
-{
-        return task_cpu(p); /* IDLE tasks as never migrated */
-}
-#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 struct task_struct *
-pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
-{
-        put_prev_task(rq, prev);
-        update_idle_core(rq);
-        schedstat_inc(rq->sched_goidle);
-
-        return rq->idle;
-}
-
-/*
- * 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_unlock_irq(&rq->lock);
-        printk(KERN_ERR "bad: scheduling from the idle thread!\n");
-        dump_stack();
-        raw_spin_lock_irq(&rq->lock);
-}
-
-static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
-{
-}
-
-/*
- * 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 set_curr_task_idle(struct rq *rq)
-{
-}
-
-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 unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
-{
-        return 0;
-}
-
-static void update_curr_idle(struct rq *rq)
-{
-}
-
-/*
- * Simple, special scheduling class for the per-CPU idle tasks:
- */
-const struct sched_class idle_sched_class = {
-        /* .next is NULL */
-        /* 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,
-
-#ifdef CONFIG_SMP
-        .select_task_rq         = select_task_rq_idle,
-        .set_cpus_allowed       = set_cpus_allowed_common,
-#endif
-
-        .set_curr_task          = set_curr_task_idle,
-        .task_tick              = task_tick_idle,
-
-        .get_rr_interval        = get_rr_interval_idle,
-
-        .prio_changed           = prio_changed_idle,
-        .switched_to            = switched_to_idle,
-        .update_curr            = update_curr_idle,
-};