| /* |
| * 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> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/rcu.h> |
| |
| #include "rcu.h" |
| |
| #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); |
| #endif |
| |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| |
| int 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. |
| */ |
| int rcu_read_lock_bh_held(void) |
| { |
| if (!debug_lockdep_rcu_enabled()) |
| return 1; |
| if (rcu_is_cpu_idle()) |
| 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_init is called when: |
| * - an active object is initialized |
| */ |
| static int rcuhead_fixup_init(void *addr, enum debug_obj_state state) |
| { |
| struct rcu_head *head = addr; |
| |
| switch (state) { |
| case ODEBUG_STATE_ACTIVE: |
| /* |
| * Ensure that queued callbacks are all executed. |
| * If we detect that we are nested in a RCU read-side critical |
| * section, we should simply fail, otherwise we would deadlock. |
| * In !PREEMPT configurations, there is no way to tell if we are |
| * in a RCU read-side critical section or not, so we never |
| * attempt any fixup and just print a warning. |
| */ |
| #ifndef CONFIG_PREEMPT |
| WARN_ON_ONCE(1); |
| return 0; |
| #endif |
| if (rcu_preempt_depth() != 0 || preempt_count() != 0 || |
| irqs_disabled()) { |
| WARN_ON_ONCE(1); |
| return 0; |
| } |
| rcu_barrier(); |
| rcu_barrier_sched(); |
| rcu_barrier_bh(); |
| debug_object_init(head, &rcuhead_debug_descr); |
| return 1; |
| default: |
| return 0; |
| } |
| } |
| |
| /* |
| * 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; |
| |
| case ODEBUG_STATE_ACTIVE: |
| /* |
| * Ensure that queued callbacks are all executed. |
| * If we detect that we are nested in a RCU read-side critical |
| * section, we should simply fail, otherwise we would deadlock. |
| * In !PREEMPT configurations, there is no way to tell if we are |
| * in a RCU read-side critical section or not, so we never |
| * attempt any fixup and just print a warning. |
| */ |
| #ifndef CONFIG_PREEMPT |
| WARN_ON_ONCE(1); |
| return 0; |
| #endif |
| if (rcu_preempt_depth() != 0 || preempt_count() != 0 || |
| irqs_disabled()) { |
| WARN_ON_ONCE(1); |
| return 0; |
| } |
| rcu_barrier(); |
| rcu_barrier_sched(); |
| rcu_barrier_bh(); |
| debug_object_activate(head, &rcuhead_debug_descr); |
| return 1; |
| default: |
| return 0; |
| } |
| } |
| |
| /* |
| * fixup_free is called when: |
| * - an active object is freed |
| */ |
| static int rcuhead_fixup_free(void *addr, enum debug_obj_state state) |
| { |
| struct rcu_head *head = addr; |
| |
| switch (state) { |
| case ODEBUG_STATE_ACTIVE: |
| /* |
| * Ensure that queued callbacks are all executed. |
| * If we detect that we are nested in a RCU read-side critical |
| * section, we should simply fail, otherwise we would deadlock. |
| * In !PREEMPT configurations, there is no way to tell if we are |
| * in a RCU read-side critical section or not, so we never |
| * attempt any fixup and just print a warning. |
| */ |
| #ifndef CONFIG_PREEMPT |
| WARN_ON_ONCE(1); |
| return 0; |
| #endif |
| if (rcu_preempt_depth() != 0 || preempt_count() != 0 || |
| irqs_disabled()) { |
| WARN_ON_ONCE(1); |
| return 0; |
| } |
| rcu_barrier(); |
| rcu_barrier_sched(); |
| rcu_barrier_bh(); |
| debug_object_free(head, &rcuhead_debug_descr); |
| return 1; |
| default: |
| return 0; |
| } |
| } |
| |
| /** |
| * 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_init = rcuhead_fixup_init, |
| .fixup_activate = rcuhead_fixup_activate, |
| .fixup_free = rcuhead_fixup_free, |
| }; |
| 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(char *rcutorturename, struct rcu_head *rhp) |
| { |
| trace_rcu_torture_read(rcutorturename, rhp); |
| } |
| EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read); |
| #else |
| #define do_trace_rcu_torture_read(rcutorturename, rhp) do { } while (0) |
| #endif |