// SPDX-License-Identifier: GPL-2.0+/* * Read-Copy Update mechanism for mutual exclusion * * 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@linux.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/signal.h>#include <linux/sched/debug.h>#include <linux/torture.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/moduleparam.h>#include <linux/kthread.h>#include <linux/tick.h>#include <linux/rcupdate_wait.h>#include <linux/sched/isolation.h>#include <linux/kprobes.h>#include <linux/slab.h>#include <linux/irq_work.h>#include <linux/rcupdate_trace.h> #define CREATE_TRACE_POINTS #include "rcu.h" #ifdef MODULE_PARAM_PREFIX#undef MODULE_PARAM_PREFIX#endif#define MODULE_PARAM_PREFIX "rcupdate." #ifndef CONFIG_TINY_RCUmodule_param(rcu_expedited, int, 0444);module_param(rcu_normal, int, 0444);static int rcu_normal_after_boot = IS_ENABLED(CONFIG_PREEMPT_RT);#if !defined(CONFIG_PREEMPT_RT) || defined(CONFIG_NO_HZ_FULL)module_param(rcu_normal_after_boot, int, 0444);#endif#endif /* #ifndef CONFIG_TINY_RCU */ #ifdef CONFIG_DEBUG_LOCK_ALLOC/** * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section? * @ret: Best guess answer if lockdep cannot be relied on * * Returns true if lockdep must be ignored, in which case ``*ret`` contains * the best guess described below. Otherwise returns false, in which * case ``*ret`` tells the caller nothing and the caller should instead * consult lockdep. * * If CONFIG_DEBUG_LOCK_ALLOC is selected, set ``*ret`` to nonzero iff in an * RCU-sched read-side critical section. In absence of * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side * critical section unless it can prove otherwise. Note that disabling * of preemption (including disabling irqs) counts as an RCU-sched * read-side critical section. This is useful for debug checks in functions * that required that they be called within an RCU-sched read-side * critical section. * * Check debug_lockdep_rcu_enabled() to prevent false positives during boot * and while lockdep is disabled. * * Note that if the CPU is in the idle loop from an RCU point of view (ie: * that we are in the section between ct_idle_enter() and ct_idle_exit()) * then rcu_read_lock_held() sets ``*ret`` to false even if the CPU did an * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are * in such a section, considering these as in extended quiescent state, * so such a CPU is effectively never in an RCU read-side critical section * regardless of what RCU primitives it invokes. This state of affairs is * required --- we need to keep an RCU-free window in idle where the CPU may * possibly enter into low power mode. This way we can notice an extended * quiescent state to other CPUs that started a grace period. Otherwise * we would delay any grace period as long as we run in the idle task. * * Similarly, we avoid claiming an RCU read lock held if the current * CPU is offline. */static bool rcu_read_lock_held_common(bool *ret){ if (!debug_lockdep_rcu_enabled()) { *ret = true; return true; } if (!rcu_is_watching()) { *ret = false; return true; } if (!rcu_lockdep_current_cpu_online()) { *ret = false; return true; } return false;} int rcu_read_lock_sched_held(void){ bool ret; if (rcu_read_lock_held_common(&ret)) return ret; return lock_is_held(&rcu_sched_lock_map) || !preemptible();}EXPORT_SYMBOL(rcu_read_lock_sched_held);#endif #ifndef CONFIG_TINY_RCU /* * Should expedited grace-period primitives always fall back to their * non-expedited counterparts? Intended for use within RCU. Note * that if the user specifies both rcu_expedited and rcu_normal, then * rcu_normal wins. (Except during the time period during boot from * when the first task is spawned until the rcu_set_runtime_mode() * core_initcall() is invoked, at which point everything is expedited.) */bool rcu_gp_is_normal(void){ return READ_ONCE(rcu_normal) && rcu_scheduler_active != RCU_SCHEDULER_INIT;}EXPORT_SYMBOL_GPL(rcu_gp_is_normal); static atomic_t rcu_async_hurry_nesting = ATOMIC_INIT(1);/* * Should call_rcu() callbacks be processed with urgency or are * they OK being executed with arbitrary delays? */bool rcu_async_should_hurry(void){ return !IS_ENABLED(CONFIG_RCU_LAZY) || atomic_read(&rcu_async_hurry_nesting);}EXPORT_SYMBOL_GPL(rcu_async_should_hurry); /** * rcu_async_hurry - Make future async RCU callbacks not lazy. * * After a call to this function, future calls to call_rcu() * will be processed in a timely fashion. */void rcu_async_hurry(void){ if (IS_ENABLED(CONFIG_RCU_LAZY)) atomic_inc(&rcu_async_hurry_nesting);}EXPORT_SYMBOL_GPL(rcu_async_hurry); /** * rcu_async_relax - Make future async RCU callbacks lazy. * * After a call to this function, future calls to call_rcu() * will be processed in a lazy fashion. */void rcu_async_relax(void){ if (IS_ENABLED(CONFIG_RCU_LAZY)) atomic_dec(&rcu_async_hurry_nesting);}EXPORT_SYMBOL_GPL(rcu_async_relax); static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1);/* * Should normal grace-period primitives be expedited? Intended for * use within RCU. Note that this function takes the rcu_expedited * sysfs/boot variable and rcu_scheduler_active into account as well * as the rcu_expedite_gp() nesting. So looping on rcu_unexpedite_gp() * until rcu_gp_is_expedited() returns false is a -really- bad idea. */bool rcu_gp_is_expedited(void){ return rcu_expedited || atomic_read(&rcu_expedited_nesting);}EXPORT_SYMBOL_GPL(rcu_gp_is_expedited); /** * rcu_expedite_gp - Expedite future RCU grace periods * * After a call to this function, future calls to synchronize_rcu() and * friends act as the corresponding synchronize_rcu_expedited() function * had instead been called. */void rcu_expedite_gp(void){ atomic_inc(&rcu_expedited_nesting);}EXPORT_SYMBOL_GPL(rcu_expedite_gp); /** * rcu_unexpedite_gp - Cancel prior rcu_expedite_gp() invocation * * Undo a prior call to rcu_expedite_gp(). If all prior calls to * rcu_expedite_gp() are undone by a subsequent call to rcu_unexpedite_gp(), * and if the rcu_expedited sysfs/boot parameter is not set, then all * subsequent calls to synchronize_rcu() and friends will return to * their normal non-expedited behavior. */void rcu_unexpedite_gp(void){ atomic_dec(&rcu_expedited_nesting);}EXPORT_SYMBOL_GPL(rcu_unexpedite_gp); static bool rcu_boot_ended __read_mostly; /* * Inform RCU of the end of the in-kernel boot sequence. */void rcu_end_inkernel_boot(void){ rcu_unexpedite_gp(); rcu_async_relax(); if (rcu_normal_after_boot) WRITE_ONCE(rcu_normal, 1); rcu_boot_ended = true;} /* * Let rcutorture know when it is OK to turn it up to eleven. */bool rcu_inkernel_boot_has_ended(void){ return rcu_boot_ended;}EXPORT_SYMBOL_GPL(rcu_inkernel_boot_has_ended); #endif /* #ifndef CONFIG_TINY_RCU */ /* * Test each non-SRCU synchronous grace-period wait API. This is * useful just after a change in mode for these primitives, and * during early boot. */void rcu_test_sync_prims(void){ if (!IS_ENABLED(CONFIG_PROVE_RCU)) return; pr_info("Running RCU synchronous self tests\n"); synchronize_rcu(); synchronize_rcu_expedited();} #if !defined(CONFIG_TINY_RCU) /* * Switch to run-time mode once RCU has fully initialized. */static int __init rcu_set_runtime_mode(void){ rcu_test_sync_prims(); rcu_scheduler_active = RCU_SCHEDULER_RUNNING; kfree_rcu_scheduler_running(); rcu_test_sync_prims(); return 0;}core_initcall(rcu_set_runtime_mode); #endif /* #if !defined(CONFIG_TINY_RCU) */ #ifdef CONFIG_DEBUG_LOCK_ALLOCstatic struct lock_class_key rcu_lock_key;struct lockdep_map rcu_lock_map = { .name = "rcu_read_lock", .key = &rcu_lock_key, .wait_type_outer = LD_WAIT_FREE, .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_RT implies PREEMPT_RCU */};EXPORT_SYMBOL_GPL(rcu_lock_map); static struct lock_class_key rcu_bh_lock_key;struct lockdep_map rcu_bh_lock_map = { .name = "rcu_read_lock_bh", .key = &rcu_bh_lock_key, .wait_type_outer = LD_WAIT_FREE, .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_RT makes BH preemptible. */};EXPORT_SYMBOL_GPL(rcu_bh_lock_map); static struct lock_class_key rcu_sched_lock_key;struct lockdep_map rcu_sched_lock_map = { .name = "rcu_read_lock_sched", .key = &rcu_sched_lock_key, .wait_type_outer = LD_WAIT_FREE, .wait_type_inner = LD_WAIT_SPIN,};EXPORT_SYMBOL_GPL(rcu_sched_lock_map); // Tell lockdep when RCU callbacks are being invoked.static struct lock_class_key rcu_callback_key;struct lockdep_map rcu_callback_map = STATIC_LOCKDEP_MAP_INIT("rcu_callback", &rcu_callback_key);EXPORT_SYMBOL_GPL(rcu_callback_map); noinstr int notrace debug_lockdep_rcu_enabled(void){ return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && READ_ONCE(debug_locks) && current->lockdep_recursion == 0;}EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); /** * rcu_read_lock_held() - might we be in RCU read-side critical section? * * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, * this assumes we are in an RCU read-side critical section unless it can * prove otherwise. This is useful for debug checks in functions that * require that they be called within an RCU read-side critical section. * * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot * and while lockdep is disabled. * * Note that rcu_read_lock() and the matching rcu_read_unlock() must * occur in the same context, for example, it is illegal to invoke * rcu_read_unlock() in process context if the matching rcu_read_lock() * was invoked from within an irq handler. * * 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_held(void){ bool ret; if (rcu_read_lock_held_common(&ret)) return ret; return lock_is_held(&rcu_lock_map);}EXPORT_SYMBOL_GPL(rcu_read_lock_held); /** * 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_bh() 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){ bool ret; if (rcu_read_lock_held_common(&ret)) return ret; return in_softirq() || irqs_disabled();}EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); int rcu_read_lock_any_held(void){ bool ret; if (rcu_read_lock_held_common(&ret)) return ret; if (lock_is_held(&rcu_lock_map) || lock_is_held(&rcu_bh_lock_map) || lock_is_held(&rcu_sched_lock_map)) return 1; return !preemptible();}EXPORT_SYMBOL_GPL(rcu_read_lock_any_held); #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ /** * wakeme_after_rcu() - Callback function to awaken a task after grace period * @head: Pointer to rcu_head member within rcu_synchronize structure * * Awaken the corresponding task now that a grace period has elapsed. */void wakeme_after_rcu(struct rcu_head *head){ struct rcu_synchronize *rcu; rcu = container_of(head, struct rcu_synchronize, head); complete(&rcu->completion);}EXPORT_SYMBOL_GPL(wakeme_after_rcu); void __wait_rcu_gp(bool checktiny, unsigned int state, int n, call_rcu_func_t *crcu_array, struct rcu_synchronize *rs_array){ int i; int j; /* Initialize and register callbacks for each crcu_array element. */ for (i = 0; i < n; i++) { if (checktiny && (crcu_array[i] == call_rcu)) { might_sleep(); continue; } for (j = 0; j < i; j++) if (crcu_array[j] == crcu_array[i]) break; if (j == i) { init_rcu_head_on_stack(&rs_array[i].head); init_completion(&rs_array[i].completion); (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu); } } /* Wait for all callbacks to be invoked. */ for (i = 0; i < n; i++) { if (checktiny && (crcu_array[i] == call_rcu)) continue; for (j = 0; j < i; j++) if (crcu_array[j] == crcu_array[i]) break; if (j == i) { wait_for_completion_state(&rs_array[i].completion, state); destroy_rcu_head_on_stack(&rs_array[i].head); } }}EXPORT_SYMBOL_GPL(__wait_rcu_gp); void finish_rcuwait(struct rcuwait *w){ rcu_assign_pointer(w->task, NULL); __set_current_state(TASK_RUNNING);}EXPORT_SYMBOL_GPL(finish_rcuwait); #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEADvoid init_rcu_head(struct rcu_head *head){ debug_object_init(head, &rcuhead_debug_descr);}EXPORT_SYMBOL_GPL(init_rcu_head); void destroy_rcu_head(struct rcu_head *head){ debug_object_free(head, &rcuhead_debug_descr);}EXPORT_SYMBOL_GPL(destroy_rcu_head); static bool rcuhead_is_static_object(void *addr){ return true;} /** * 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.Lines 1–500 of 678. Load more
// SPDX-License-Identifier: GPL-2.0+ /* * Read-Copy Update mechanism for mutual exclusion * * 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@linux.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/signal.h> #include <linux/sched/debug.h> #include <linux/torture.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/moduleparam.h> #include <linux/kthread.h> #include <linux/tick.h> #include <linux/rcupdate_wait.h> #include <linux/sched/isolation.h> #include <linux/kprobes.h> #include <linux/slab.h> #include <linux/irq_work.h> #include <linux/rcupdate_trace.h> #define CREATE_TRACE_POINTS #include "rcu.h" #ifdef MODULE_PARAM_PREFIX #undef MODULE_PARAM_PREFIX #endif #define MODULE_PARAM_PREFIX "rcupdate." #ifndef CONFIG_TINY_RCU module_param(rcu_expedited, int, 0444); module_param(rcu_normal, int, 0444); static int rcu_normal_after_boot = IS_ENABLED(CONFIG_PREEMPT_RT); #if !defined(CONFIG_PREEMPT_RT) || defined(CONFIG_NO_HZ_FULL) module_param(rcu_normal_after_boot, int, 0444); #endif #endif /* #ifndef CONFIG_TINY_RCU */ #ifdef CONFIG_DEBUG_LOCK_ALLOC /** * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section? * @ret: Best guess answer if lockdep cannot be relied on * * Returns true if lockdep must be ignored, in which case ``*ret`` contains * the best guess described below. Otherwise returns false, in which * case ``*ret`` tells the caller nothing and the caller should instead * consult lockdep. * * If CONFIG_DEBUG_LOCK_ALLOC is selected, set ``*ret`` to nonzero iff in an * RCU-sched read-side critical section. In absence of * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side * critical section unless it can prove otherwise. Note that disabling * of preemption (including disabling irqs) counts as an RCU-sched * read-side critical section. This is useful for debug checks in functions * that required that they be called within an RCU-sched read-side * critical section. * * Check debug_lockdep_rcu_enabled() to prevent false positives during boot * and while lockdep is disabled. * * Note that if the CPU is in the idle loop from an RCU point of view (ie: * that we are in the section between ct_idle_enter() and ct_idle_exit()) * then rcu_read_lock_held() sets ``*ret`` to false even if the CPU did an * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are * in such a section, considering these as in extended quiescent state, * so such a CPU is effectively never in an RCU read-side critical section * regardless of what RCU primitives it invokes. This state of affairs is * required --- we need to keep an RCU-free window in idle where the CPU may * possibly enter into low power mode. This way we can notice an extended * quiescent state to other CPUs that started a grace period. Otherwise * we would delay any grace period as long as we run in the idle task. * * Similarly, we avoid claiming an RCU read lock held if the current * CPU is offline. */ static bool rcu_read_lock_held_common(bool *ret) { if (!debug_lockdep_rcu_enabled()) { *ret = true; return true; } if (!rcu_is_watching()) { *ret = false; return true; } if (!rcu_lockdep_current_cpu_online()) { *ret = false; return true; } return false; } int rcu_read_lock_sched_held(void) { bool ret; if (rcu_read_lock_held_common(&ret)) return ret; return lock_is_held(&rcu_sched_lock_map) || !preemptible(); } EXPORT_SYMBOL(rcu_read_lock_sched_held); #endif #ifndef CONFIG_TINY_RCU /* * Should expedited grace-period primitives always fall back to their * non-expedited counterparts? Intended for use within RCU. Note * that if the user specifies both rcu_expedited and rcu_normal, then * rcu_normal wins. (Except during the time period during boot from * when the first task is spawned until the rcu_set_runtime_mode() * core_initcall() is invoked, at which point everything is expedited.) */ bool rcu_gp_is_normal(void) { return READ_ONCE(rcu_normal) && rcu_scheduler_active != RCU_SCHEDULER_INIT; } EXPORT_SYMBOL_GPL(rcu_gp_is_normal); static atomic_t rcu_async_hurry_nesting = ATOMIC_INIT(1); /* * Should call_rcu() callbacks be processed with urgency or are * they OK being executed with arbitrary delays? */ bool rcu_async_should_hurry(void) { return !IS_ENABLED(CONFIG_RCU_LAZY) || atomic_read(&rcu_async_hurry_nesting); } EXPORT_SYMBOL_GPL(rcu_async_should_hurry); /** * rcu_async_hurry - Make future async RCU callbacks not lazy. * * After a call to this function, future calls to call_rcu() * will be processed in a timely fashion. */ void rcu_async_hurry(void) { if (IS_ENABLED(CONFIG_RCU_LAZY)) atomic_inc(&rcu_async_hurry_nesting); } EXPORT_SYMBOL_GPL(rcu_async_hurry); /** * rcu_async_relax - Make future async RCU callbacks lazy. * * After a call to this function, future calls to call_rcu() * will be processed in a lazy fashion. */ void rcu_async_relax(void) { if (IS_ENABLED(CONFIG_RCU_LAZY)) atomic_dec(&rcu_async_hurry_nesting); } EXPORT_SYMBOL_GPL(rcu_async_relax); static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1); /* * Should normal grace-period primitives be expedited? Intended for * use within RCU. Note that this function takes the rcu_expedited * sysfs/boot variable and rcu_scheduler_active into account as well * as the rcu_expedite_gp() nesting. So looping on rcu_unexpedite_gp() * until rcu_gp_is_expedited() returns false is a -really- bad idea. */ bool rcu_gp_is_expedited(void) { return rcu_expedited || atomic_read(&rcu_expedited_nesting); } EXPORT_SYMBOL_GPL(rcu_gp_is_expedited); /** * rcu_expedite_gp - Expedite future RCU grace periods * * After a call to this function, future calls to synchronize_rcu() and * friends act as the corresponding synchronize_rcu_expedited() function * had instead been called. */ void rcu_expedite_gp(void) { atomic_inc(&rcu_expedited_nesting); } EXPORT_SYMBOL_GPL(rcu_expedite_gp); /** * rcu_unexpedite_gp - Cancel prior rcu_expedite_gp() invocation * * Undo a prior call to rcu_expedite_gp(). If all prior calls to * rcu_expedite_gp() are undone by a subsequent call to rcu_unexpedite_gp(), * and if the rcu_expedited sysfs/boot parameter is not set, then all * subsequent calls to synchronize_rcu() and friends will return to * their normal non-expedited behavior. */ void rcu_unexpedite_gp(void) { atomic_dec(&rcu_expedited_nesting); } EXPORT_SYMBOL_GPL(rcu_unexpedite_gp); static bool rcu_boot_ended __read_mostly; /* * Inform RCU of the end of the in-kernel boot sequence. */ void rcu_end_inkernel_boot(void) { rcu_unexpedite_gp(); rcu_async_relax(); if (rcu_normal_after_boot) WRITE_ONCE(rcu_normal, 1); rcu_boot_ended = true; } /* * Let rcutorture know when it is OK to turn it up to eleven. */ bool rcu_inkernel_boot_has_ended(void) { return rcu_boot_ended; } EXPORT_SYMBOL_GPL(rcu_inkernel_boot_has_ended); #endif /* #ifndef CONFIG_TINY_RCU */ /* * Test each non-SRCU synchronous grace-period wait API. This is * useful just after a change in mode for these primitives, and * during early boot. */ void rcu_test_sync_prims(void) { if (!IS_ENABLED(CONFIG_PROVE_RCU)) return; pr_info("Running RCU synchronous self tests\n"); synchronize_rcu(); synchronize_rcu_expedited(); } #if !defined(CONFIG_TINY_RCU) /* * Switch to run-time mode once RCU has fully initialized. */ static int __init rcu_set_runtime_mode(void) { rcu_test_sync_prims(); rcu_scheduler_active = RCU_SCHEDULER_RUNNING; kfree_rcu_scheduler_running(); rcu_test_sync_prims(); return 0; } core_initcall(rcu_set_runtime_mode); #endif /* #if !defined(CONFIG_TINY_RCU) */ #ifdef CONFIG_DEBUG_LOCK_ALLOC static struct lock_class_key rcu_lock_key; struct lockdep_map rcu_lock_map = { .name = "rcu_read_lock", .key = &rcu_lock_key, .wait_type_outer = LD_WAIT_FREE, .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_RT implies PREEMPT_RCU */ }; EXPORT_SYMBOL_GPL(rcu_lock_map); static struct lock_class_key rcu_bh_lock_key; struct lockdep_map rcu_bh_lock_map = { .name = "rcu_read_lock_bh", .key = &rcu_bh_lock_key, .wait_type_outer = LD_WAIT_FREE, .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_RT makes BH preemptible. */ }; EXPORT_SYMBOL_GPL(rcu_bh_lock_map); static struct lock_class_key rcu_sched_lock_key; struct lockdep_map rcu_sched_lock_map = { .name = "rcu_read_lock_sched", .key = &rcu_sched_lock_key, .wait_type_outer = LD_WAIT_FREE, .wait_type_inner = LD_WAIT_SPIN, }; EXPORT_SYMBOL_GPL(rcu_sched_lock_map); // Tell lockdep when RCU callbacks are being invoked. static struct lock_class_key rcu_callback_key; struct lockdep_map rcu_callback_map = STATIC_LOCKDEP_MAP_INIT("rcu_callback", &rcu_callback_key); EXPORT_SYMBOL_GPL(rcu_callback_map); noinstr int notrace debug_lockdep_rcu_enabled(void) { return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && READ_ONCE(debug_locks) && current->lockdep_recursion == 0; } EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); /** * rcu_read_lock_held() - might we be in RCU read-side critical section? * * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, * this assumes we are in an RCU read-side critical section unless it can * prove otherwise. This is useful for debug checks in functions that * require that they be called within an RCU read-side critical section. * * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot * and while lockdep is disabled. * * Note that rcu_read_lock() and the matching rcu_read_unlock() must * occur in the same context, for example, it is illegal to invoke * rcu_read_unlock() in process context if the matching rcu_read_lock() * was invoked from within an irq handler. * * 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_held(void) { bool ret; if (rcu_read_lock_held_common(&ret)) return ret; return lock_is_held(&rcu_lock_map); } EXPORT_SYMBOL_GPL(rcu_read_lock_held); /** * 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_bh() 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) { bool ret; if (rcu_read_lock_held_common(&ret)) return ret; return in_softirq() || irqs_disabled(); } EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); int rcu_read_lock_any_held(void) { bool ret; if (rcu_read_lock_held_common(&ret)) return ret; if (lock_is_held(&rcu_lock_map) || lock_is_held(&rcu_bh_lock_map) || lock_is_held(&rcu_sched_lock_map)) return 1; return !preemptible(); } EXPORT_SYMBOL_GPL(rcu_read_lock_any_held); #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ /** * wakeme_after_rcu() - Callback function to awaken a task after grace period * @head: Pointer to rcu_head member within rcu_synchronize structure * * Awaken the corresponding task now that a grace period has elapsed. */ void wakeme_after_rcu(struct rcu_head *head) { struct rcu_synchronize *rcu; rcu = container_of(head, struct rcu_synchronize, head); complete(&rcu->completion); } EXPORT_SYMBOL_GPL(wakeme_after_rcu); void __wait_rcu_gp(bool checktiny, unsigned int state, int n, call_rcu_func_t *crcu_array, struct rcu_synchronize *rs_array) { int i; int j; /* Initialize and register callbacks for each crcu_array element. */ for (i = 0; i < n; i++) { if (checktiny && (crcu_array[i] == call_rcu)) { might_sleep(); continue; } for (j = 0; j < i; j++) if (crcu_array[j] == crcu_array[i]) break; if (j == i) { init_rcu_head_on_stack(&rs_array[i].head); init_completion(&rs_array[i].completion); (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu); } } /* Wait for all callbacks to be invoked. */ for (i = 0; i < n; i++) { if (checktiny && (crcu_array[i] == call_rcu)) continue; for (j = 0; j < i; j++) if (crcu_array[j] == crcu_array[i]) break; if (j == i) { wait_for_completion_state(&rs_array[i].completion, state); destroy_rcu_head_on_stack(&rs_array[i].head); } } } EXPORT_SYMBOL_GPL(__wait_rcu_gp); void finish_rcuwait(struct rcuwait *w) { rcu_assign_pointer(w->task, NULL); __set_current_state(TASK_RUNNING); } EXPORT_SYMBOL_GPL(finish_rcuwait); #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD void init_rcu_head(struct rcu_head *head) { debug_object_init(head, &rcuhead_debug_descr); } EXPORT_SYMBOL_GPL(init_rcu_head); void destroy_rcu_head(struct rcu_head *head) { debug_object_free(head, &rcuhead_debug_descr); } EXPORT_SYMBOL_GPL(destroy_rcu_head); static bool rcuhead_is_static_object(void *addr) { return true; } /** * 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.