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Commit 7e42776d authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Drive TASKS_RCU directly off of PREEMPT 



The actual use of TASKS_RCU is only when PREEMPT, otherwise RCU-sched
is used instead.  This commit therefore makes synchronize_rcu_tasks()
and call_rcu_tasks() available always, but mapped to synchronize_sched()
and call_rcu_sched(), respectively, when !PREEMPT.  This approach also
allows some #ifdefs to be removed from rcutorture.

Reported-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
parent 8be6e1b1

include/linux/rcupdate.h

+4 −2
Original line number Diff line number Diff line
@@ -58,8 +58,6 @@ void call_rcu(struct rcu_head *head, rcu_callback_t func); 
void call_rcu_bh(struct rcu_head *head, rcu_callback_t func);

void call_rcu_sched(struct rcu_head *head, rcu_callback_t func);

void synchronize_sched(void);

void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func);

void synchronize_rcu_tasks(void);

void rcu_barrier_tasks(void);



#ifdef CONFIG_PREEMPT_RCU
@@ -176,10 +174,14 @@ extern struct srcu_struct tasks_rcu_exit_srcu; 
		rcu_all_qs(); \

		rcu_note_voluntary_context_switch_lite(t); \

	} while (0)

void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func);

void synchronize_rcu_tasks(void);

#else /* #ifdef CONFIG_TASKS_RCU */

#define TASKS_RCU(x) do { } while (0)

#define rcu_note_voluntary_context_switch_lite(t)	do { } while (0)

#define rcu_note_voluntary_context_switch(t)		rcu_all_qs()

#define call_rcu_tasks call_rcu_sched

#define synchronize_rcu_tasks synchronize_sched

#endif /* #else #ifdef CONFIG_TASKS_RCU */



/**

kernel/rcu/Kconfig

+1 −2
Original line number Diff line number Diff line
@@ -69,8 +69,7 @@ config TREE_SRCU 
	  This option selects the full-fledged version of SRCU.



config TASKS_RCU

	bool

	default n

	def_bool PREEMPT

	select SRCU

	help

	  This option enables a task-based RCU implementation that uses

kernel/rcu/rcutorture.c

+1 −16
Original line number Diff line number Diff line
@@ -696,8 +696,6 @@ static struct rcu_torture_ops sched_ops = { 
	.name		= "sched"

};



#ifdef CONFIG_TASKS_RCU



/*

 * Definitions for RCU-tasks torture testing.

 */
@@ -735,24 +733,11 @@ static struct rcu_torture_ops tasks_ops = { 
	.name		= "tasks"

};



#define RCUTORTURE_TASKS_OPS &tasks_ops,



static bool __maybe_unused torturing_tasks(void)

{

	return cur_ops == &tasks_ops;

}



#else /* #ifdef CONFIG_TASKS_RCU */



#define RCUTORTURE_TASKS_OPS



static bool __maybe_unused torturing_tasks(void)

{

	return false;

}



#endif /* #else #ifdef CONFIG_TASKS_RCU */



/*

 * RCU torture priority-boost testing.  Runs one real-time thread per

 * CPU for moderate bursts, repeatedly registering RCU callbacks and
@@ -1749,7 +1734,7 @@ rcu_torture_init(void) 
	int firsterr = 0;

	static struct rcu_torture_ops *torture_ops[] = {

		&rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,

		&sched_ops, RCUTORTURE_TASKS_OPS

		&sched_ops, &tasks_ops,

	};



	if (!torture_init_begin(torture_type, verbose, &torture_runnable))

tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt

+1 −1
Original line number Diff line number Diff line
@@ -69,11 +69,11 @@ CONFIG_RCU_TORTURE_TEST_RUNNABLE 
CONFIG_PREEMPT_RCU

CONFIG_TREE_RCU

CONFIG_TINY_RCU

CONFIG_TASKS_RCU



	These are controlled by CONFIG_PREEMPT and/or CONFIG_SMP.



CONFIG_SRCU

CONFIG_TASKS_RCU



	Selected by CONFIG_RCU_TORTURE_TEST, so cannot disable.