Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 9dc5ad32 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Simplify RCU_TINY RCU callback invocation 



TINY_PREEMPT_RCU could use a kthread to handle RCU callback invocation,
which required an API to abstract kthread vs. softirq invocation.
Now that TINY_PREEMPT_RCU is no longer with us, this commit retires
this API in favor of direct use of the relevant softirq primitives.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 58c4e69d

include/linux/rcupdate.h

+1 −0
Original line number Diff line number Diff line
@@ -216,6 +216,7 @@ static inline int rcu_preempt_depth(void) 
#endif /* #else #ifdef CONFIG_PREEMPT_RCU */



/* Internal to kernel */

extern void rcu_init(void);

extern void rcu_sched_qs(int cpu);

extern void rcu_bh_qs(int cpu);

extern void rcu_check_callbacks(int cpu, int user);

include/linux/rcutiny.h

+0 −4
Original line number Diff line number Diff line
@@ -27,10 +27,6 @@ 


#include <linux/cache.h>



static inline void rcu_init(void)

{

}



static inline void rcu_barrier_bh(void)

{

	wait_rcu_gp(call_rcu_bh);

include/linux/rcutree.h

+0 −1
Original line number Diff line number Diff line
@@ -30,7 +30,6 @@ 
#ifndef __LINUX_RCUTREE_H

#define __LINUX_RCUTREE_H



extern void rcu_init(void);

extern void rcu_note_context_switch(int cpu);

extern int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies);

extern void rcu_cpu_stall_reset(void);

kernel/rcutiny.c

+9 −5
Original line number Diff line number Diff line
@@ -44,7 +44,6 @@ 


/* Forward declarations for rcutiny_plugin.h. */

struct rcu_ctrlblk;

static void invoke_rcu_callbacks(void);

static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp);

static void rcu_process_callbacks(struct softirq_action *unused);

static void __call_rcu(struct rcu_head *head,
@@ -227,7 +226,7 @@ void rcu_sched_qs(int cpu) 
	local_irq_save(flags);

	if (rcu_qsctr_help(&rcu_sched_ctrlblk) +

	    rcu_qsctr_help(&rcu_bh_ctrlblk))

		invoke_rcu_callbacks();

		raise_softirq(RCU_SOFTIRQ);

	local_irq_restore(flags);

}
@@ -240,7 +239,7 @@ void rcu_bh_qs(int cpu) 


	local_irq_save(flags);

	if (rcu_qsctr_help(&rcu_bh_ctrlblk))

		invoke_rcu_callbacks();

		raise_softirq(RCU_SOFTIRQ);

	local_irq_restore(flags);

}
@@ -277,7 +276,7 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp) 
					      ACCESS_ONCE(rcp->rcucblist),

					      need_resched(),

					      is_idle_task(current),

					      rcu_is_callbacks_kthread()));

					      false));

		return;

	}
@@ -307,7 +306,7 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp) 
	RCU_TRACE(rcu_trace_sub_qlen(rcp, cb_count));

	RCU_TRACE(trace_rcu_batch_end(rcp->name, cb_count, 0, need_resched(),

				      is_idle_task(current),

				      rcu_is_callbacks_kthread()));

				      false));

}



static void rcu_process_callbacks(struct softirq_action *unused)
@@ -379,3 +378,8 @@ void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) 
	__call_rcu(head, func, &rcu_bh_ctrlblk);

}

EXPORT_SYMBOL_GPL(call_rcu_bh);



void rcu_init(void)

{

	open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);

}

kernel/rcutiny_plugin.h

+0 −33
Original line number Diff line number Diff line
@@ -102,39 +102,6 @@ static void check_cpu_stalls(void) 
	RCU_TRACE(check_cpu_stall_preempt());

}



/* Hold off callback invocation until early_initcall() time. */

static int rcu_scheduler_fully_active __read_mostly;



/*

 * Start up softirq processing of callbacks.

 */

void invoke_rcu_callbacks(void)

{

	if (rcu_scheduler_fully_active)

		raise_softirq(RCU_SOFTIRQ);

}



#ifdef CONFIG_RCU_TRACE



/*

 * There is no callback kthread, so this thread is never it.

 */

static bool rcu_is_callbacks_kthread(void)

{

	return false;

}



#endif /* #ifdef CONFIG_RCU_TRACE */



static int __init rcu_scheduler_really_started(void)

{

	rcu_scheduler_fully_active = 1;

	open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);

	raise_softirq(RCU_SOFTIRQ);  /* Invoke any callbacks from early boot. */

	return 0;

}

early_initcall(rcu_scheduler_really_started);



#ifdef CONFIG_DEBUG_LOCK_ALLOC

#include <linux/kernel_stat.h>