From 900b1028ec388e50c98200641ae4274794c807cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 10 Feb 2017 14:32:54 -0800 Subject: [PATCH] srcu: Allow SRCU to access rcu_scheduler_active This is primarily a code-movement commit in preparation for allowing SRCU to handle early-boot SRCU grace periods. Signed-off-by: Paul E. McKenney --- include/linux/rcutiny.h | 6 ++--- kernel/rcu/tiny_plugin.h | 9 +++---- kernel/rcu/tree.c | 2 +- kernel/rcu/tree_exp.h | 12 ---------- kernel/rcu/update.c | 52 ++++++++++++++++++++++++++-------------- 5 files changed, 43 insertions(+), 38 deletions(-) diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 6c9d941e3962..5219be250f00 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -217,14 +217,14 @@ static inline void exit_rcu(void) { } -#ifdef CONFIG_DEBUG_LOCK_ALLOC +#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) extern int rcu_scheduler_active __read_mostly; void rcu_scheduler_starting(void); -#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ +#else /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */ static inline void rcu_scheduler_starting(void) { } -#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ +#endif /* #else #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */ #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) diff --git a/kernel/rcu/tiny_plugin.h b/kernel/rcu/tiny_plugin.h index df3a60e19f07..371034e77f87 100644 --- a/kernel/rcu/tiny_plugin.h +++ b/kernel/rcu/tiny_plugin.h @@ -52,7 +52,7 @@ static struct rcu_ctrlblk rcu_bh_ctrlblk = { RCU_TRACE(.name = "rcu_bh") }; -#ifdef CONFIG_DEBUG_LOCK_ALLOC +#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) #include int rcu_scheduler_active __read_mostly; @@ -65,15 +65,16 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active); * to RCU_SCHEDULER_RUNNING, skipping the RCU_SCHEDULER_INIT stage. * The reason for this is that Tiny RCU does not need kthreads, so does * not have to care about the fact that the scheduler is half-initialized - * at a certain phase of the boot process. + * at a certain phase of the boot process. Unless SRCU is in the mix. */ void __init rcu_scheduler_starting(void) { WARN_ON(nr_context_switches() > 0); - rcu_scheduler_active = RCU_SCHEDULER_RUNNING; + rcu_scheduler_active = IS_ENABLED(CONFIG_SRCU) + ? RCU_SCHEDULER_INIT : RCU_SCHEDULER_RUNNING; } -#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ +#endif /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */ #ifdef CONFIG_RCU_TRACE diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 8cc9d40b41ea..2380d1e3dfb8 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3974,7 +3974,7 @@ early_initcall(rcu_spawn_gp_kthread); * task is booting the system, and such primitives are no-ops). After this * function is called, any synchronous grace-period primitives are run as * expedited, with the requesting task driving the grace period forward. - * A later core_initcall() rcu_exp_runtime_mode() will switch to full + * A later core_initcall() rcu_set_runtime_mode() will switch to full * runtime RCU functionality. */ void rcu_scheduler_starting(void) diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index a1f52bbe9db6..51ca287828a2 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -737,15 +737,3 @@ void synchronize_rcu_expedited(void) EXPORT_SYMBOL_GPL(synchronize_rcu_expedited); #endif /* #else #ifdef CONFIG_PREEMPT_RCU */ - -/* - * Switch to run-time mode once Tree RCU has fully initialized. - */ -static int __init rcu_exp_runtime_mode(void) -{ - rcu_test_sync_prims(); - rcu_scheduler_active = RCU_SCHEDULER_RUNNING; - rcu_test_sync_prims(); - return 0; -} -core_initcall(rcu_exp_runtime_mode); diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index 55c8530316c7..c5df0d756900 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -124,7 +124,7 @@ EXPORT_SYMBOL(rcu_read_lock_sched_held); * non-expedited counterparts? Intended for use within RCU. Note * that if the user specifies both rcu_expedited and rcu_normal, then * rcu_normal wins. (Except during the time period during boot from - * when the first task is spawned until the rcu_exp_runtime_mode() + * when the first task is spawned until the rcu_set_runtime_mode() * core_initcall() is invoked, at which point everything is expedited.) */ bool rcu_gp_is_normal(void) @@ -190,6 +190,39 @@ void rcu_end_inkernel_boot(void) #endif /* #ifndef CONFIG_TINY_RCU */ +/* + * Test each non-SRCU synchronous grace-period wait API. This is + * useful just after a change in mode for these primitives, and + * during early boot. + */ +void rcu_test_sync_prims(void) +{ + if (!IS_ENABLED(CONFIG_PROVE_RCU)) + return; + synchronize_rcu(); + synchronize_rcu_bh(); + synchronize_sched(); + synchronize_rcu_expedited(); + synchronize_rcu_bh_expedited(); + synchronize_sched_expedited(); +} + +#if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) + +/* + * Switch to run-time mode once RCU has fully initialized. + */ +static int __init rcu_set_runtime_mode(void) +{ + rcu_test_sync_prims(); + rcu_scheduler_active = RCU_SCHEDULER_RUNNING; + rcu_test_sync_prims(); + return 0; +} +core_initcall(rcu_set_runtime_mode); + +#endif /* #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) */ + #ifdef CONFIG_PREEMPT_RCU /* @@ -817,23 +850,6 @@ static void rcu_spawn_tasks_kthread(void) #endif /* #ifdef CONFIG_TASKS_RCU */ -/* - * Test each non-SRCU synchronous grace-period wait API. This is - * useful just after a change in mode for these primitives, and - * during early boot. - */ -void rcu_test_sync_prims(void) -{ - if (!IS_ENABLED(CONFIG_PROVE_RCU)) - return; - synchronize_rcu(); - synchronize_rcu_bh(); - synchronize_sched(); - synchronize_rcu_expedited(); - synchronize_rcu_bh_expedited(); - synchronize_sched_expedited(); -} - #ifdef CONFIG_PROVE_RCU /*