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Commit bbad9379 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: slim down rcutiny by removing rcu_scheduler_active and friends 



TINY_RCU does not need rcu_scheduler_active unless CONFIG_DEBUG_LOCK_ALLOC.
So conditionally compile rcu_scheduler_active in order to slim down
rcutiny a bit more.  Also gets rid of an EXPORT_SYMBOL_GPL, which is
responsible for most of the slimming.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 25502a6c

include/linux/rcupdate.h

+1 −3
Original line number Diff line number Diff line
@@ -64,8 +64,6 @@ extern int sched_expedited_torture_stats(char *page); 


/* Internal to kernel */

extern void rcu_init(void);

extern int rcu_scheduler_active;

extern void rcu_scheduler_starting(void);



#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)

#include <linux/rcutree.h>
@@ -178,7 +176,7 @@ static inline int rcu_read_lock_bh_held(void) 
#ifdef CONFIG_PREEMPT

static inline int rcu_read_lock_sched_held(void)

{

	return !rcu_scheduler_active || preempt_count() != 0 || irqs_disabled();

	return preempt_count() != 0 || irqs_disabled();

}

#else /* #ifdef CONFIG_PREEMPT */

static inline int rcu_read_lock_sched_held(void)

include/linux/rcutiny.h

+13 −0
Original line number Diff line number Diff line
@@ -128,4 +128,17 @@ static inline int rcu_preempt_depth(void) 
	return 0;

}



#ifdef CONFIG_DEBUG_LOCK_ALLOC



extern int rcu_scheduler_active __read_mostly;

extern void rcu_scheduler_starting(void);



#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */



static inline void rcu_scheduler_starting(void)

{

}



#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */



#endif /* __LINUX_RCUTINY_H */

include/linux/rcutree.h

+3 −0
Original line number Diff line number Diff line
@@ -123,4 +123,7 @@ static inline int rcu_blocking_is_gp(void) 
	return num_online_cpus() == 1;

}



extern void rcu_scheduler_starting(void);

extern int rcu_scheduler_active __read_mostly;



#endif /* __LINUX_RCUTREE_H */

kernel/rcupdate.c

+0 −19
Original line number Diff line number Diff line
@@ -44,7 +44,6 @@ 
#include <linux/cpu.h>

#include <linux/mutex.h>

#include <linux/module.h>

#include <linux/kernel_stat.h>

#include <linux/hardirq.h>



#ifdef CONFIG_DEBUG_LOCK_ALLOC
@@ -64,9 +63,6 @@ struct lockdep_map rcu_sched_lock_map = 
EXPORT_SYMBOL_GPL(rcu_sched_lock_map);

#endif



int rcu_scheduler_active __read_mostly;

EXPORT_SYMBOL_GPL(rcu_scheduler_active);



#ifdef CONFIG_DEBUG_LOCK_ALLOC



int debug_lockdep_rcu_enabled(void)
@@ -96,21 +92,6 @@ EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); 


#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */



/*

 * This function is invoked towards the end of the scheduler's initialization

 * process.  Before this is called, the idle task might contain

 * RCU read-side critical sections (during which time, this idle

 * task is booting the system).  After this function is called, the

 * idle tasks are prohibited from containing RCU read-side critical

 * sections.

 */

void rcu_scheduler_starting(void)

{

	WARN_ON(num_online_cpus() != 1);

	WARN_ON(nr_context_switches() > 0);

	rcu_scheduler_active = 1;

}



/*

 * Awaken the corresponding synchronize_rcu() instance now that a

 * grace period has elapsed.

kernel/rcutiny.c

+7 −0
Original line number Diff line number Diff line
@@ -54,6 +54,11 @@ static struct rcu_ctrlblk rcu_bh_ctrlblk = { 
	.curtail	= &rcu_bh_ctrlblk.rcucblist,

};



#ifdef CONFIG_DEBUG_LOCK_ALLOC

int rcu_scheduler_active __read_mostly;

EXPORT_SYMBOL_GPL(rcu_scheduler_active);

#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */



#ifdef CONFIG_NO_HZ



static long rcu_dynticks_nesting = 1;
@@ -276,3 +281,5 @@ void __init rcu_init(void) 
{

	open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);

}



#include "rcutiny_plugin.h"