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Commit 2439b696 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Shrink TINY_RCU by moving exit_rcu() 



Now that TINY_PREEMPT_RCU is no more, exit_rcu() is always an empty
function.  But if TINY_RCU is going to have an empty function, it should
be in include/linux/rcutiny.h, where it does not bloat the kernel.
This commit therefore moves exit_rcu() out of kernel/rcupdate.c to
kernel/rcutree_plugin.h, and places a static inline empty function in
include/linux/rcutiny.h in order to shrink TINY_RCU a bit.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 7807acdb

include/linux/rcupdate.h

+0 −2
Original line number Diff line number Diff line
@@ -240,8 +240,6 @@ static inline void rcu_user_hooks_switch(struct task_struct *prev, 
					 struct task_struct *next) { }

#endif /* CONFIG_RCU_USER_QS */



extern void exit_rcu(void);



/**

 * RCU_NONIDLE - Indicate idle-loop code that needs RCU readers

 * @a: Code that RCU needs to pay attention to.

include/linux/rcutiny.h

+4 −0
Original line number Diff line number Diff line
@@ -119,6 +119,10 @@ static inline void rcu_cpu_stall_reset(void) 
{

}



static inline void exit_rcu(void)

{

}



#ifdef CONFIG_DEBUG_LOCK_ALLOC

extern int rcu_scheduler_active __read_mostly;

extern void rcu_scheduler_starting(void);

include/linux/rcutree.h

+2 −0
Original line number Diff line number Diff line
@@ -85,6 +85,8 @@ extern void rcu_force_quiescent_state(void); 
extern void rcu_bh_force_quiescent_state(void);

extern void rcu_sched_force_quiescent_state(void);



extern void exit_rcu(void);



extern void rcu_scheduler_starting(void);

extern int rcu_scheduler_active __read_mostly;

kernel/rcupdate.c

+1 −25
Original line number Diff line number Diff line
@@ -104,31 +104,7 @@ void __rcu_read_unlock(void) 
}

EXPORT_SYMBOL_GPL(__rcu_read_unlock);



/*

 * Check for a task exiting while in a preemptible-RCU read-side

 * critical section, clean up if so.  No need to issue warnings,

 * as debug_check_no_locks_held() already does this if lockdep

 * is enabled.

 */

void exit_rcu(void)

{

	struct task_struct *t = current;



	if (likely(list_empty(&current->rcu_node_entry)))

		return;

	t->rcu_read_lock_nesting = 1;

	barrier();

	t->rcu_read_unlock_special = RCU_READ_UNLOCK_BLOCKED;

	__rcu_read_unlock();

}



#else /* #ifdef CONFIG_PREEMPT_RCU */



void exit_rcu(void)

{

}



#endif /* #else #ifdef CONFIG_PREEMPT_RCU */

#endif /* #ifdef CONFIG_PREEMPT_RCU */



#ifdef CONFIG_DEBUG_LOCK_ALLOC

static struct lock_class_key rcu_lock_key;

kernel/rcutree_plugin.h

+26 −0
Original line number Diff line number Diff line
@@ -932,6 +932,24 @@ static void __init __rcu_init_preempt(void) 
	rcu_init_one(&rcu_preempt_state, &rcu_preempt_data);

}



/*

 * Check for a task exiting while in a preemptible-RCU read-side

 * critical section, clean up if so.  No need to issue warnings,

 * as debug_check_no_locks_held() already does this if lockdep

 * is enabled.

 */

void exit_rcu(void)

{

	struct task_struct *t = current;



	if (likely(list_empty(&current->rcu_node_entry)))

		return;

	t->rcu_read_lock_nesting = 1;

	barrier();

	t->rcu_read_unlock_special = RCU_READ_UNLOCK_BLOCKED;

	__rcu_read_unlock();

}



#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */



static struct rcu_state *rcu_state = &rcu_sched_state;
@@ -1100,6 +1118,14 @@ static void __init __rcu_init_preempt(void) 
{

}



/*

 * Because preemptible RCU does not exist, tasks cannot possibly exit

 * while in preemptible RCU read-side critical sections.

 */

void exit_rcu(void)

{

}



#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */



#ifdef CONFIG_RCU_BOOST