diff options
Diffstat (limited to 'kernel/rcutiny.c')
| -rw-r--r-- | kernel/rcutiny.c | 385 |
1 files changed, 0 insertions, 385 deletions
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c deleted file mode 100644 index 9ed6075dc56..00000000000 --- a/kernel/rcutiny.c +++ /dev/null @@ -1,385 +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/completion.h> -#include <linux/interrupt.h> -#include <linux/notifier.h> -#include <linux/rcupdate.h> -#include <linux/kernel.h> -#include <linux/export.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> -#include <linux/prefetch.h> - -#ifdef CONFIG_RCU_TRACE -#include <trace/events/rcu.h> -#endif /* #else #ifdef CONFIG_RCU_TRACE */ - -#include "rcu.h" - -/* Forward declarations for rcutiny_plugin.h. */ -struct rcu_ctrlblk; -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, - void (*func)(struct rcu_head *rcu), - struct rcu_ctrlblk *rcp); - -static long long rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE; - -#include "rcutiny_plugin.h" - -/* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */ -static void rcu_idle_enter_common(long long newval) -{ - if (newval) { - RCU_TRACE(trace_rcu_dyntick("--=", - rcu_dynticks_nesting, newval)); - rcu_dynticks_nesting = newval; - return; - } - RCU_TRACE(trace_rcu_dyntick("Start", rcu_dynticks_nesting, newval)); - if (!is_idle_task(current)) { - struct task_struct *idle = idle_task(smp_processor_id()); - - RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task", - rcu_dynticks_nesting, newval)); - ftrace_dump(DUMP_ALL); - WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", - current->pid, current->comm, - idle->pid, idle->comm); /* must be idle task! */ - } - rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ - barrier(); - rcu_dynticks_nesting = newval; -} - -/* - * Enter idle, 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_idle_enter(void) -{ - unsigned long flags; - long long newval; - - local_irq_save(flags); - WARN_ON_ONCE((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0); - if ((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == - DYNTICK_TASK_NEST_VALUE) - newval = 0; - else - newval = rcu_dynticks_nesting - DYNTICK_TASK_NEST_VALUE; - rcu_idle_enter_common(newval); - local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(rcu_idle_enter); - -/* - * Exit an interrupt handler towards idle. - */ -void rcu_irq_exit(void) -{ - unsigned long flags; - long long newval; - - local_irq_save(flags); - newval = rcu_dynticks_nesting - 1; - WARN_ON_ONCE(newval < 0); - rcu_idle_enter_common(newval); - local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(rcu_irq_exit); - -/* Common code for rcu_idle_exit() and rcu_irq_enter(), see kernel/rcutree.c. */ -static void rcu_idle_exit_common(long long oldval) -{ - if (oldval) { - RCU_TRACE(trace_rcu_dyntick("++=", - oldval, rcu_dynticks_nesting)); - return; - } - RCU_TRACE(trace_rcu_dyntick("End", oldval, rcu_dynticks_nesting)); - if (!is_idle_task(current)) { - struct task_struct *idle = idle_task(smp_processor_id()); - - RCU_TRACE(trace_rcu_dyntick("Error on exit: not idle task", - oldval, rcu_dynticks_nesting)); - ftrace_dump(DUMP_ALL); - WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", - current->pid, current->comm, - idle->pid, idle->comm); /* must be idle task! */ - } -} - -/* - * Exit idle, so that we are no longer in an extended quiescent state. - */ -void rcu_idle_exit(void) -{ - unsigned long flags; - long long oldval; - - local_irq_save(flags); - oldval = rcu_dynticks_nesting; - WARN_ON_ONCE(rcu_dynticks_nesting < 0); - if (rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) - rcu_dynticks_nesting += DYNTICK_TASK_NEST_VALUE; - else - rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE; - rcu_idle_exit_common(oldval); - local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(rcu_idle_exit); - -/* - * Enter an interrupt handler, moving away from idle. - */ -void rcu_irq_enter(void) -{ - unsigned long flags; - long long oldval; - - local_irq_save(flags); - oldval = rcu_dynticks_nesting; - rcu_dynticks_nesting++; - WARN_ON_ONCE(rcu_dynticks_nesting == 0); - rcu_idle_exit_common(oldval); - local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(rcu_irq_enter); - -#ifdef CONFIG_DEBUG_LOCK_ALLOC - -/* - * Test whether RCU thinks that the current CPU is idle. - */ -int rcu_is_cpu_idle(void) -{ - return !rcu_dynticks_nesting; -} -EXPORT_SYMBOL(rcu_is_cpu_idle); - -#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ - -/* - * Test whether the current CPU was interrupted from idle. Nested - * interrupts don't count, we must be running at the first interrupt - * level. - */ -static int rcu_is_cpu_rrupt_from_idle(void) -{ - return rcu_dynticks_nesting <= 1; -} - -/* - * Helper function for rcu_sched_qs() and rcu_bh_qs(). - * Also irqs are disabled to avoid confusion due to interrupt handlers - * invoking call_rcu(). - */ -static int rcu_qsctr_help(struct rcu_ctrlblk *rcp) -{ - RCU_TRACE(reset_cpu_stall_ticks(rcp)); - if (rcp->rcucblist != NULL && - rcp->donetail != rcp->curtail) { - rcp->donetail = rcp->curtail; - return 1; - } - - 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) -{ - unsigned long flags; - - local_irq_save(flags); - if (rcu_qsctr_help(&rcu_sched_ctrlblk) + - rcu_qsctr_help(&rcu_bh_ctrlblk)) - raise_softirq(RCU_SOFTIRQ); - local_irq_restore(flags); -} - -/* - * Record an rcu_bh quiescent state. - */ -void rcu_bh_qs(int cpu) -{ - unsigned long flags; - - local_irq_save(flags); - if (rcu_qsctr_help(&rcu_bh_ctrlblk)) - raise_softirq(RCU_SOFTIRQ); - local_irq_restore(flags); -} - -/* - * Check to see if the scheduling-clock interrupt came from an extended - * quiescent state, and, if so, tell RCU about it. This function must - * be called from hardirq context. It is normally called from the - * scheduling-clock interrupt. - */ -void rcu_check_callbacks(int cpu, int user) -{ - RCU_TRACE(check_cpu_stalls()); - if (user || rcu_is_cpu_rrupt_from_idle()) - rcu_sched_qs(cpu); - else if (!in_softirq()) - rcu_bh_qs(cpu); -} - -/* - * Invoke the RCU callbacks on the specified rcu_ctrlkblk structure - * whose grace period has elapsed. - */ -static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp) -{ - const char *rn = NULL; - 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) { - RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, 0, -1)); - RCU_TRACE(trace_rcu_batch_end(rcp->name, 0, - ACCESS_ONCE(rcp->rcucblist), - need_resched(), - is_idle_task(current), - false)); - return; - } - - /* Move the ready-to-invoke callbacks to a local list. */ - local_irq_save(flags); - RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, rcp->qlen, -1)); - list = rcp->rcucblist; - rcp->rcucblist = *rcp->donetail; - *rcp->donetail = NULL; - if (rcp->curtail == rcp->donetail) - rcp->curtail = &rcp->rcucblist; - rcp->donetail = &rcp->rcucblist; - local_irq_restore(flags); - - /* Invoke the callbacks on the local list. */ - RCU_TRACE(rn = rcp->name); - while (list) { - next = list->next; - prefetch(next); - debug_rcu_head_unqueue(list); - local_bh_disable(); - __rcu_reclaim(rn, list); - local_bh_enable(); - list = next; - RCU_TRACE(cb_count++); - } - 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), - false)); -} - -static void rcu_process_callbacks(struct softirq_action *unused) -{ - __rcu_process_callbacks(&rcu_sched_ctrlblk); - __rcu_process_callbacks(&rcu_bh_ctrlblk); -} - -/* - * 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) -{ - rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) && - !lock_is_held(&rcu_lock_map) && - !lock_is_held(&rcu_sched_lock_map), - "Illegal synchronize_sched() in RCU read-side critical section"); - 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_init(void) -{ - open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); -} |