Commit 1b04fa99 authored by Uladzislau Rezki (Sony)'s avatar Uladzislau Rezki (Sony) Committed by Paul E. McKenney
Browse files

rcu-tasks: Move RCU-tasks initialization to before early_initcall() 

PowerPC testing encountered boot failures due to RCU Tasks not being
fully initialized until core_initcall() time.  This commit therefore
initializes RCU Tasks (along with Rude RCU and RCU Tasks Trace) just
before early_initcall() time, thus allowing waiting on RCU Tasks grace
periods from early_initcall() handlers.

Link: https://lore.kernel.org/rcu/87eekfh80a.fsf@dja-thinkpad.axtens.net/


Fixes: 36dadef2 ("kprobes: Init kprobes in early_initcall")
Tested-by: default avatarDaniel Axtens <dja@axtens.net>
Signed-off-by: default avatarUladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 0477e928

include/linux/rcupdate.h

+6 −0
Original line number Diff line number Diff line
@@ -86,6 +86,12 @@ void rcu_sched_clock_irq(int user); 
void rcu_report_dead(unsigned int cpu);

void rcutree_migrate_callbacks(int cpu);



#ifdef CONFIG_TASKS_RCU_GENERIC

void rcu_init_tasks_generic(void);

#else

static inline void rcu_init_tasks_generic(void) { }

#endif



#ifdef CONFIG_RCU_STALL_COMMON

void rcu_sysrq_start(void);

void rcu_sysrq_end(void);

init/main.c

+1 −0
Original line number Diff line number Diff line
@@ -1512,6 +1512,7 @@ static noinline void __init kernel_init_freeable(void) 


	init_mm_internals();



	rcu_init_tasks_generic();

	do_pre_smp_initcalls();

	lockup_detector_init();

kernel/rcu/tasks.h

+21 −4
Original line number Diff line number Diff line
@@ -241,7 +241,7 @@ static int __noreturn rcu_tasks_kthread(void *arg) 
	}

}



/* Spawn RCU-tasks grace-period kthread, e.g., at core_initcall() time. */

/* Spawn RCU-tasks grace-period kthread. */

static void __init rcu_spawn_tasks_kthread_generic(struct rcu_tasks *rtp)

{

	struct task_struct *t;
@@ -569,7 +569,6 @@ static int __init rcu_spawn_tasks_kthread(void) 
	rcu_spawn_tasks_kthread_generic(&rcu_tasks);

	return 0;

}

core_initcall(rcu_spawn_tasks_kthread);



#ifndef CONFIG_TINY_RCU

static void show_rcu_tasks_classic_gp_kthread(void)
@@ -697,7 +696,6 @@ static int __init rcu_spawn_tasks_rude_kthread(void) 
	rcu_spawn_tasks_kthread_generic(&rcu_tasks_rude);

	return 0;

}

core_initcall(rcu_spawn_tasks_rude_kthread);



#ifndef CONFIG_TINY_RCU

static void show_rcu_tasks_rude_gp_kthread(void)
@@ -975,6 +973,11 @@ static void rcu_tasks_trace_pregp_step(void) 
static void rcu_tasks_trace_pertask(struct task_struct *t,

				    struct list_head *hop)

{

	// During early boot when there is only the one boot CPU, there

	// is no idle task for the other CPUs. Just return.

	if (unlikely(t == NULL))

		return;



	WRITE_ONCE(t->trc_reader_special.b.need_qs, false);

	WRITE_ONCE(t->trc_reader_checked, false);

	t->trc_ipi_to_cpu = -1;
@@ -1200,7 +1203,6 @@ static int __init rcu_spawn_tasks_trace_kthread(void) 
	rcu_spawn_tasks_kthread_generic(&rcu_tasks_trace);

	return 0;

}

core_initcall(rcu_spawn_tasks_trace_kthread);



#ifndef CONFIG_TINY_RCU

static void show_rcu_tasks_trace_gp_kthread(void)
@@ -1229,6 +1231,21 @@ void show_rcu_tasks_gp_kthreads(void) 
}

#endif /* #ifndef CONFIG_TINY_RCU */



void __init rcu_init_tasks_generic(void)

{

#ifdef CONFIG_TASKS_RCU

	rcu_spawn_tasks_kthread();

#endif



#ifdef CONFIG_TASKS_RUDE_RCU

	rcu_spawn_tasks_rude_kthread();

#endif



#ifdef CONFIG_TASKS_TRACE_RCU

	rcu_spawn_tasks_trace_kthread();

#endif

}



#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */

static inline void rcu_tasks_bootup_oddness(void) {}

void show_rcu_tasks_gp_kthreads(void) {}