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rcu: Simplify RCU_TINY RCU callback invocation

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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: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Paul E. McKenney 2013-03-27 10:11:15 -07:00
parent 58c4e69d43
commit 9dc5ad3248
5 changed files with 10 additions and 43 deletions
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1
include/linux/rcupdate.h
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@ -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);

4
include/linux/rcutiny.h
View File

@ -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);

1
include/linux/rcutree.h
View File

@ -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);

14
kernel/rcutiny.c
View File

@ -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);
}

33
kernel/rcutiny_plugin.h
View File

@ -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>