Commit 23c22d91 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Boqun Feng
Browse files

rcu-tasks: Move RCU Tasks self-tests to core_initcall() 



The timer and hrtimer softirq processing has moved to dedicated threads
for kernels built with CONFIG_IRQ_FORCED_THREADING=y.  This results in
timers not expiring until later in early boot, which in turn causes the
RCU Tasks self-tests to hang in kernels built with CONFIG_PROVE_RCU=y,
which further causes the entire kernel to hang.  One fix would be to
make timers work during this time, but there are no known users of RCU
Tasks grace periods during that time, so no justification for the added
complexity.  Not yet, anyway.

This commit therefore moves the call to rcu_init_tasks_generic() from
kernel_init_freeable() to a core_initcall().  This works because the
timer and hrtimer kthreads are created at early_initcall() time.

Fixes: 49a17639 ("softirq: Use a dedicated thread for timer wakeups on PREEMPT_RT.")
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: <linux-trace-kernel@vger.kernel.org>
Tested-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarBoqun Feng <boqun.feng@gmail.com>
parent 85aad7cc

include/linux/rcupdate.h

+0 −6
Original line number Diff line number Diff line
@@ -121,12 +121,6 @@ void rcu_init(void); 
extern int rcu_scheduler_active;

void rcu_sched_clock_irq(int user);



#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

+0 −1
Original line number Diff line number Diff line
@@ -1553,7 +1553,6 @@ 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

+4 −1
Original line number Diff line number Diff line
@@ -2256,7 +2256,7 @@ void __init tasks_cblist_init_generic(void) 
#endif

}



void __init rcu_init_tasks_generic(void)

static int __init rcu_init_tasks_generic(void)

{

#ifdef CONFIG_TASKS_RCU

	rcu_spawn_tasks_kthread();
@@ -2272,7 +2272,10 @@ void __init rcu_init_tasks_generic(void) 


	// Run the self-tests.

	rcu_tasks_initiate_self_tests();



	return 0;

}

core_initcall(rcu_init_tasks_generic);



#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */

static inline void rcu_tasks_bootup_oddness(void) {}