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rcu: Drive TASKS_RCU directly off of PREEMPT

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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: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Paul E. McKenney 2017-05-25 08:05:00 -07:00
parent 8be6e1b15c
commit 7e42776d5e
4 changed files with 7 additions and 21 deletions
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6
include/linux/rcupdate.h
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@ -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 */
/**

3
kernel/rcu/Kconfig
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@ -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

17
kernel/rcu/rcutorture.c
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@ -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))

2
tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt
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@ -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.