diff options
Diffstat (limited to 'kernel/rcupdate.c')
| -rw-r--r-- | kernel/rcupdate.c | 341 |
1 files changed, 0 insertions, 341 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c deleted file mode 100644 index b02a339836b..00000000000 --- a/kernel/rcupdate.c +++ /dev/null @@ -1,341 +0,0 @@ -/* - * Read-Copy Update mechanism for mutual exclusion - * - * 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, 2001 - * - * Authors: Dipankar Sarma <dipankar@in.ibm.com> - * Manfred Spraul <manfred@colorfullife.com> - * - * Based on the original work by Paul McKenney <paulmck@us.ibm.com> - * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. - * Papers: - * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf - * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) - * - * For detailed explanation of Read-Copy Update mechanism see - - * http://lse.sourceforge.net/locking/rcupdate.html - * - */ -#include <linux/types.h> -#include <linux/kernel.h> -#include <linux/init.h> -#include <linux/spinlock.h> -#include <linux/smp.h> -#include <linux/interrupt.h> -#include <linux/sched.h> -#include <linux/atomic.h> -#include <linux/bitops.h> -#include <linux/percpu.h> -#include <linux/notifier.h> -#include <linux/cpu.h> -#include <linux/mutex.h> -#include <linux/export.h> -#include <linux/hardirq.h> -#include <linux/delay.h> -#include <linux/module.h> - -#define CREATE_TRACE_POINTS -#include <trace/events/rcu.h> - -#include "rcu.h" - -module_param(rcu_expedited, int, 0); - -#ifdef CONFIG_PREEMPT_RCU - -/* - * Preemptible RCU implementation for rcu_read_lock(). - * Just increment ->rcu_read_lock_nesting, shared state will be updated - * if we block. - */ -void __rcu_read_lock(void) -{ - current->rcu_read_lock_nesting++; - barrier(); /* critical section after entry code. */ -} -EXPORT_SYMBOL_GPL(__rcu_read_lock); - -/* - * Preemptible RCU implementation for rcu_read_unlock(). - * Decrement ->rcu_read_lock_nesting. If the result is zero (outermost - * rcu_read_unlock()) and ->rcu_read_unlock_special is non-zero, then - * invoke rcu_read_unlock_special() to clean up after a context switch - * in an RCU read-side critical section and other special cases. - */ -void __rcu_read_unlock(void) -{ - struct task_struct *t = current; - - if (t->rcu_read_lock_nesting != 1) { - --t->rcu_read_lock_nesting; - } else { - barrier(); /* critical section before exit code. */ - t->rcu_read_lock_nesting = INT_MIN; -#ifdef CONFIG_PROVE_RCU_DELAY - udelay(10); /* Make preemption more probable. */ -#endif /* #ifdef CONFIG_PROVE_RCU_DELAY */ - barrier(); /* assign before ->rcu_read_unlock_special load */ - if (unlikely(ACCESS_ONCE(t->rcu_read_unlock_special))) - rcu_read_unlock_special(t); - barrier(); /* ->rcu_read_unlock_special load before assign */ - t->rcu_read_lock_nesting = 0; - } -#ifdef CONFIG_PROVE_LOCKING - { - int rrln = ACCESS_ONCE(t->rcu_read_lock_nesting); - - WARN_ON_ONCE(rrln < 0 && rrln > INT_MIN / 2); - } -#endif /* #ifdef CONFIG_PROVE_LOCKING */ -} -EXPORT_SYMBOL_GPL(__rcu_read_unlock); - -#endif /* #ifdef CONFIG_PREEMPT_RCU */ - -#ifdef CONFIG_DEBUG_LOCK_ALLOC -static struct lock_class_key rcu_lock_key; -struct lockdep_map rcu_lock_map = - STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key); -EXPORT_SYMBOL_GPL(rcu_lock_map); - -static struct lock_class_key rcu_bh_lock_key; -struct lockdep_map rcu_bh_lock_map = - STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key); -EXPORT_SYMBOL_GPL(rcu_bh_lock_map); - -static struct lock_class_key rcu_sched_lock_key; -struct lockdep_map rcu_sched_lock_map = - STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key); -EXPORT_SYMBOL_GPL(rcu_sched_lock_map); - -int notrace debug_lockdep_rcu_enabled(void) -{ - return rcu_scheduler_active && debug_locks && - current->lockdep_recursion == 0; -} -EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); - -/** - * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section? - * - * Check for bottom half being disabled, which covers both the - * CONFIG_PROVE_RCU and not cases. Note that if someone uses - * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled) - * will show the situation. This is useful for debug checks in functions - * that require that they be called within an RCU read-side critical - * section. - * - * Check debug_lockdep_rcu_enabled() to prevent false positives during boot. - * - * Note that rcu_read_lock() is disallowed if the CPU is either idle or - * offline from an RCU perspective, so check for those as well. - */ -int rcu_read_lock_bh_held(void) -{ - if (!debug_lockdep_rcu_enabled()) - return 1; - if (rcu_is_cpu_idle()) - return 0; - if (!rcu_lockdep_current_cpu_online()) - return 0; - return in_softirq() || irqs_disabled(); -} -EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); - -#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ - -struct rcu_synchronize { - struct rcu_head head; - struct completion completion; -}; - -/* - * Awaken the corresponding synchronize_rcu() instance now that a - * grace period has elapsed. - */ -static void wakeme_after_rcu(struct rcu_head *head) -{ - struct rcu_synchronize *rcu; - - rcu = container_of(head, struct rcu_synchronize, head); - complete(&rcu->completion); -} - -void wait_rcu_gp(call_rcu_func_t crf) -{ - struct rcu_synchronize rcu; - - init_rcu_head_on_stack(&rcu.head); - init_completion(&rcu.completion); - /* Will wake me after RCU finished. */ - crf(&rcu.head, wakeme_after_rcu); - /* Wait for it. */ - wait_for_completion(&rcu.completion); - destroy_rcu_head_on_stack(&rcu.head); -} -EXPORT_SYMBOL_GPL(wait_rcu_gp); - -#ifdef CONFIG_PROVE_RCU -/* - * wrapper function to avoid #include problems. - */ -int rcu_my_thread_group_empty(void) -{ - return thread_group_empty(current); -} -EXPORT_SYMBOL_GPL(rcu_my_thread_group_empty); -#endif /* #ifdef CONFIG_PROVE_RCU */ - -#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD -static inline void debug_init_rcu_head(struct rcu_head *head) -{ - debug_object_init(head, &rcuhead_debug_descr); -} - -static inline void debug_rcu_head_free(struct rcu_head *head) -{ - debug_object_free(head, &rcuhead_debug_descr); -} - -/* - * fixup_activate is called when: - * - an active object is activated - * - an unknown object is activated (might be a statically initialized object) - * Activation is performed internally by call_rcu(). - */ -static int rcuhead_fixup_activate(void *addr, enum debug_obj_state state) -{ - struct rcu_head *head = addr; - - switch (state) { - - case ODEBUG_STATE_NOTAVAILABLE: - /* - * This is not really a fixup. We just make sure that it is - * tracked in the object tracker. - */ - debug_object_init(head, &rcuhead_debug_descr); - debug_object_activate(head, &rcuhead_debug_descr); - return 0; - default: - return 1; - } -} - -/** - * init_rcu_head_on_stack() - initialize on-stack rcu_head for debugobjects - * @head: pointer to rcu_head structure to be initialized - * - * This function informs debugobjects of a new rcu_head structure that - * has been allocated as an auto variable on the stack. This function - * is not required for rcu_head structures that are statically defined or - * that are dynamically allocated on the heap. This function has no - * effect for !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds. - */ -void init_rcu_head_on_stack(struct rcu_head *head) -{ - debug_object_init_on_stack(head, &rcuhead_debug_descr); -} -EXPORT_SYMBOL_GPL(init_rcu_head_on_stack); - -/** - * destroy_rcu_head_on_stack() - destroy on-stack rcu_head for debugobjects - * @head: pointer to rcu_head structure to be initialized - * - * This function informs debugobjects that an on-stack rcu_head structure - * is about to go out of scope. As with init_rcu_head_on_stack(), this - * function is not required for rcu_head structures that are statically - * defined or that are dynamically allocated on the heap. Also as with - * init_rcu_head_on_stack(), this function has no effect for - * !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds. - */ -void destroy_rcu_head_on_stack(struct rcu_head *head) -{ - debug_object_free(head, &rcuhead_debug_descr); -} -EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack); - -struct debug_obj_descr rcuhead_debug_descr = { - .name = "rcu_head", - .fixup_activate = rcuhead_fixup_activate, -}; -EXPORT_SYMBOL_GPL(rcuhead_debug_descr); -#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ - -#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) || defined(CONFIG_RCU_TRACE) -void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp, - unsigned long secs, - unsigned long c_old, unsigned long c) -{ - trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c); -} -EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read); -#else -#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \ - do { } while (0) -#endif - -#ifdef CONFIG_RCU_STALL_COMMON - -#ifdef CONFIG_PROVE_RCU -#define RCU_STALL_DELAY_DELTA (5 * HZ) -#else -#define RCU_STALL_DELAY_DELTA 0 -#endif - -int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */ -int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT; - -module_param(rcu_cpu_stall_suppress, int, 0644); -module_param(rcu_cpu_stall_timeout, int, 0644); - -int rcu_jiffies_till_stall_check(void) -{ - int till_stall_check = ACCESS_ONCE(rcu_cpu_stall_timeout); - - /* - * Limit check must be consistent with the Kconfig limits - * for CONFIG_RCU_CPU_STALL_TIMEOUT. - */ - if (till_stall_check < 3) { - ACCESS_ONCE(rcu_cpu_stall_timeout) = 3; - till_stall_check = 3; - } else if (till_stall_check > 300) { - ACCESS_ONCE(rcu_cpu_stall_timeout) = 300; - till_stall_check = 300; - } - return till_stall_check * HZ + RCU_STALL_DELAY_DELTA; -} - -static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) -{ - rcu_cpu_stall_suppress = 1; - return NOTIFY_DONE; -} - -static struct notifier_block rcu_panic_block = { - .notifier_call = rcu_panic, -}; - -static int __init check_cpu_stall_init(void) -{ - atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); - return 0; -} -early_initcall(check_cpu_stall_init); - -#endif /* #ifdef CONFIG_RCU_STALL_COMMON */ |