diff options
Diffstat (limited to 'kernel/rcutiny.c')
| -rw-r--r-- | kernel/rcutiny.c | 324 |
1 files changed, 0 insertions, 324 deletions
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c deleted file mode 100644 index 0c343b9a46d..00000000000 --- a/kernel/rcutiny.c +++ /dev/null @@ -1,324 +0,0 @@ -/* - * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition. - * - * 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, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. - * - * Copyright IBM Corporation, 2008 - * - * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> - * - * For detailed explanation of Read-Copy Update mechanism see - - * Documentation/RCU - */ -#include <linux/moduleparam.h> -#include <linux/completion.h> -#include <linux/interrupt.h> -#include <linux/notifier.h> -#include <linux/rcupdate.h> -#include <linux/kernel.h> -#include <linux/module.h> -#include <linux/mutex.h> -#include <linux/sched.h> -#include <linux/types.h> -#include <linux/init.h> -#include <linux/time.h> -#include <linux/cpu.h> - -/* Controls for rcu_kthread() kthread, replacing RCU_SOFTIRQ used previously. */ -static struct task_struct *rcu_kthread_task; -static DECLARE_WAIT_QUEUE_HEAD(rcu_kthread_wq); -static unsigned long have_rcu_kthread_work; -static void invoke_rcu_kthread(void); - -/* Forward declarations for rcutiny_plugin.h. */ -struct rcu_ctrlblk; -static void rcu_process_callbacks(struct rcu_ctrlblk *rcp); -static int rcu_kthread(void *arg); -static void __call_rcu(struct rcu_head *head, - void (*func)(struct rcu_head *rcu), - struct rcu_ctrlblk *rcp); - -#include "rcutiny_plugin.h" - -#ifdef CONFIG_NO_HZ - -static long rcu_dynticks_nesting = 1; - -/* - * Enter dynticks-idle mode, which is an extended quiescent state - * if we have fully entered that mode (i.e., if the new value of - * dynticks_nesting is zero). - */ -void rcu_enter_nohz(void) -{ - if (--rcu_dynticks_nesting == 0) - rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ -} - -/* - * Exit dynticks-idle mode, so that we are no longer in an extended - * quiescent state. - */ -void rcu_exit_nohz(void) -{ - rcu_dynticks_nesting++; -} - -#endif /* #ifdef CONFIG_NO_HZ */ - -/* - * Helper function for rcu_qsctr_inc() and rcu_bh_qsctr_inc(). - * Also disable irqs to avoid confusion due to interrupt handlers - * invoking call_rcu(). - */ -static int rcu_qsctr_help(struct rcu_ctrlblk *rcp) -{ - unsigned long flags; - - local_irq_save(flags); - if (rcp->rcucblist != NULL && - rcp->donetail != rcp->curtail) { - rcp->donetail = rcp->curtail; - local_irq_restore(flags); - return 1; - } - local_irq_restore(flags); - - return 0; -} - -/* - * Record an rcu quiescent state. And an rcu_bh quiescent state while we - * are at it, given that any rcu quiescent state is also an rcu_bh - * quiescent state. Use "+" instead of "||" to defeat short circuiting. - */ -void rcu_sched_qs(int cpu) -{ - if (rcu_qsctr_help(&rcu_sched_ctrlblk) + - rcu_qsctr_help(&rcu_bh_ctrlblk)) - invoke_rcu_kthread(); -} - -/* - * Record an rcu_bh quiescent state. - */ -void rcu_bh_qs(int cpu) -{ - if (rcu_qsctr_help(&rcu_bh_ctrlblk)) - invoke_rcu_kthread(); -} - -/* - * Check to see if the scheduling-clock interrupt came from an extended - * quiescent state, and, if so, tell RCU about it. - */ -void rcu_check_callbacks(int cpu, int user) -{ - if (user || - (idle_cpu(cpu) && - !in_softirq() && - hardirq_count() <= (1 << HARDIRQ_SHIFT))) - rcu_sched_qs(cpu); - else if (!in_softirq()) - rcu_bh_qs(cpu); - rcu_preempt_check_callbacks(); -} - -/* - * Invoke the RCU callbacks on the specified rcu_ctrlkblk structure - * whose grace period has elapsed. - */ -static void rcu_process_callbacks(struct rcu_ctrlblk *rcp) -{ - struct rcu_head *next, *list; - unsigned long flags; - RCU_TRACE(int cb_count = 0); - - /* If no RCU callbacks ready to invoke, just return. */ - if (&rcp->rcucblist == rcp->donetail) - return; - - /* Move the ready-to-invoke callbacks to a local list. */ - local_irq_save(flags); - list = rcp->rcucblist; - rcp->rcucblist = *rcp->donetail; - *rcp->donetail = NULL; - if (rcp->curtail == rcp->donetail) - rcp->curtail = &rcp->rcucblist; - rcu_preempt_remove_callbacks(rcp); - rcp->donetail = &rcp->rcucblist; - local_irq_restore(flags); - - /* Invoke the callbacks on the local list. */ - while (list) { - next = list->next; - prefetch(next); - debug_rcu_head_unqueue(list); - local_bh_disable(); - list->func(list); - local_bh_enable(); - list = next; - RCU_TRACE(cb_count++); - } - RCU_TRACE(rcu_trace_sub_qlen(rcp, cb_count)); -} - -/* - * This kthread invokes RCU callbacks whose grace periods have - * elapsed. It is awakened as needed, and takes the place of the - * RCU_SOFTIRQ that was used previously for this purpose. - * This is a kthread, but it is never stopped, at least not until - * the system goes down. - */ -static int rcu_kthread(void *arg) -{ - unsigned long work; - unsigned long morework; - unsigned long flags; - - for (;;) { - wait_event_interruptible(rcu_kthread_wq, - have_rcu_kthread_work != 0); - morework = rcu_boost(); - local_irq_save(flags); - work = have_rcu_kthread_work; - have_rcu_kthread_work = morework; - local_irq_restore(flags); - if (work) { - rcu_process_callbacks(&rcu_sched_ctrlblk); - rcu_process_callbacks(&rcu_bh_ctrlblk); - rcu_preempt_process_callbacks(); - } - schedule_timeout_interruptible(1); /* Leave CPU for others. */ - } - - return 0; /* Not reached, but needed to shut gcc up. */ -} - -/* - * Wake up rcu_kthread() to process callbacks now eligible for invocation - * or to boost readers. - */ -static void invoke_rcu_kthread(void) -{ - unsigned long flags; - - local_irq_save(flags); - have_rcu_kthread_work = 1; - wake_up(&rcu_kthread_wq); - local_irq_restore(flags); -} - -/* - * Wait for a grace period to elapse. But it is illegal to invoke - * synchronize_sched() from within an RCU read-side critical section. - * Therefore, any legal call to synchronize_sched() is a quiescent - * state, and so on a UP system, synchronize_sched() need do nothing. - * Ditto for synchronize_rcu_bh(). (But Lai Jiangshan points out the - * benefits of doing might_sleep() to reduce latency.) - * - * Cool, huh? (Due to Josh Triplett.) - * - * But we want to make this a static inline later. The cond_resched() - * currently makes this problematic. - */ -void synchronize_sched(void) -{ - cond_resched(); -} -EXPORT_SYMBOL_GPL(synchronize_sched); - -/* - * Helper function for call_rcu() and call_rcu_bh(). - */ -static void __call_rcu(struct rcu_head *head, - void (*func)(struct rcu_head *rcu), - struct rcu_ctrlblk *rcp) -{ - unsigned long flags; - - debug_rcu_head_queue(head); - head->func = func; - head->next = NULL; - - local_irq_save(flags); - *rcp->curtail = head; - rcp->curtail = &head->next; - RCU_TRACE(rcp->qlen++); - local_irq_restore(flags); -} - -/* - * Post an RCU callback to be invoked after the end of an RCU-sched grace - * period. But since we have but one CPU, that would be after any - * quiescent state. - */ -void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) -{ - __call_rcu(head, func, &rcu_sched_ctrlblk); -} -EXPORT_SYMBOL_GPL(call_rcu_sched); - -/* - * Post an RCU bottom-half callback to be invoked after any subsequent - * quiescent state. - */ -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_barrier_bh(void) -{ - struct rcu_synchronize rcu; - - init_rcu_head_on_stack(&rcu.head); - init_completion(&rcu.completion); - /* Will wake me after RCU finished. */ - call_rcu_bh(&rcu.head, wakeme_after_rcu); - /* Wait for it. */ - wait_for_completion(&rcu.completion); - destroy_rcu_head_on_stack(&rcu.head); -} -EXPORT_SYMBOL_GPL(rcu_barrier_bh); - -void rcu_barrier_sched(void) -{ - struct rcu_synchronize rcu; - - init_rcu_head_on_stack(&rcu.head); - init_completion(&rcu.completion); - /* Will wake me after RCU finished. */ - call_rcu_sched(&rcu.head, wakeme_after_rcu); - /* Wait for it. */ - wait_for_completion(&rcu.completion); - destroy_rcu_head_on_stack(&rcu.head); -} -EXPORT_SYMBOL_GPL(rcu_barrier_sched); - -/* - * Spawn the kthread that invokes RCU callbacks. - */ -static int __init rcu_spawn_kthreads(void) -{ - struct sched_param sp; - - rcu_kthread_task = kthread_run(rcu_kthread, NULL, "rcu_kthread"); - sp.sched_priority = RCU_BOOST_PRIO; - sched_setscheduler_nocheck(rcu_kthread_task, SCHED_FIFO, &sp); - return 0; -} -early_initcall(rcu_spawn_kthreads); |