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srcu: Move rcu_scheduler_starting() from Tiny RCU to Tiny SRCU

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Other than lockdep support, Tiny RCU has no need for the
scheduler status.  However, Tiny SRCU will need this to control
boot-time behavior independent of lockdep.  Therefore, this commit
moves rcu_scheduler_starting() from kernel/rcu/tiny_plugin.h to
kernel/rcu/srcutiny.c.  This in turn allows the complete removal of
kernel/rcu/tiny_plugin.h.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2017-05-26 16:16:40 -07:00
parent 520eccdfe1
commit 825c5bd2fd
5 changed files with 12 additions and 54 deletions
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1
include/linux/rcupdate.h
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@ -105,6 +105,7 @@ static inline int rcu_preempt_depth(void)
/* Internal to kernel */ /* Internal to kernel */
void rcu_init(void); void rcu_init(void);
extern int rcu_scheduler_active __read_mostly;
void rcu_sched_qs(void); void rcu_sched_qs(void);
void rcu_bh_qs(void); void rcu_bh_qs(void);
void rcu_check_callbacks(int user); void rcu_check_callbacks(int user);

8
include/linux/rcutiny.h
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@ -116,13 +116,11 @@ static inline void rcu_irq_exit_irqson(void) { }
static inline void rcu_irq_enter_irqson(void) { } static inline void rcu_irq_enter_irqson(void) { }
static inline void rcu_irq_exit(void) { } static inline void rcu_irq_exit(void) { }
static inline void exit_rcu(void) { } static inline void exit_rcu(void) { }
#ifdef CONFIG_SRCU
#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU)
extern int rcu_scheduler_active __read_mostly;
void rcu_scheduler_starting(void); void rcu_scheduler_starting(void);
#else /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */ #else /* #ifndef CONFIG_SRCU */
static inline void rcu_scheduler_starting(void) { } static inline void rcu_scheduler_starting(void) { }
#endif /* #else #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */ #endif /* #else #ifndef CONFIG_SRCU */
static inline void rcu_end_inkernel_boot(void) { } static inline void rcu_end_inkernel_boot(void) { }
static inline bool rcu_is_watching(void) { return true; } static inline bool rcu_is_watching(void) { return true; }

8
kernel/rcu/srcutiny.c
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@ -33,6 +33,8 @@
#include "rcu_segcblist.h" #include "rcu_segcblist.h"
#include "rcu.h" #include "rcu.h"
int rcu_scheduler_active __read_mostly;
static int init_srcu_struct_fields(struct srcu_struct *sp) static int init_srcu_struct_fields(struct srcu_struct *sp)
{ {
sp->srcu_lock_nesting[0] = 0; sp->srcu_lock_nesting[0] = 0;
@ -193,3 +195,9 @@ void synchronize_srcu(struct srcu_struct *sp)
destroy_rcu_head_on_stack(&rs.head); destroy_rcu_head_on_stack(&rs.head);
} }
EXPORT_SYMBOL_GPL(synchronize_srcu); EXPORT_SYMBOL_GPL(synchronize_srcu);
/* Lockdep diagnostics. */
void __init rcu_scheduler_starting(void)
{
rcu_scheduler_active = RCU_SCHEDULER_RUNNING;
}

2
kernel/rcu/tiny.c
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@ -56,8 +56,6 @@ static struct rcu_ctrlblk rcu_bh_ctrlblk = {
.curtail = &rcu_bh_ctrlblk.rcucblist, .curtail = &rcu_bh_ctrlblk.rcucblist,
}; };
#include "tiny_plugin.h"
void rcu_barrier_bh(void) void rcu_barrier_bh(void)
{ {
wait_rcu_gp(call_rcu_bh); wait_rcu_gp(call_rcu_bh);

47
kernel/rcu/tiny_plugin.h
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@ -1,47 +0,0 @@
/*
* Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition
* Internal non-public definitions that provide either classic
* or preemptible semantics.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, you can access it online at
* http://www.gnu.org/licenses/gpl-2.0.html.
*
* Copyright (c) 2010 Linaro
*
* Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
*/
#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU)
#include <linux/kernel_stat.h>
int rcu_scheduler_active __read_mostly;
EXPORT_SYMBOL_GPL(rcu_scheduler_active);
/*
* During boot, we forgive RCU lockdep issues. After this function is
* invoked, we start taking RCU lockdep issues seriously. Note that unlike
* Tree RCU, Tiny RCU transitions directly from RCU_SCHEDULER_INACTIVE
* 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. Unless SRCU is in the mix.
*/
void __init rcu_scheduler_starting(void)
{
WARN_ON(nr_context_switches() > 0);
rcu_scheduler_active = IS_ENABLED(CONFIG_SRCU)
? RCU_SCHEDULER_INIT : RCU_SCHEDULER_RUNNING;
}
#endif /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */