// 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/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> #define CREATE_TRACE_POINTS #include "rcu.h" #ifdef MODULE_PARAM_PREFIX#undef MODULE_PARAM_PREFIX#endif#define MODULE_PARAM_PREFIX "rcupdate." #ifndef CONFIG_TINY_RCUextern int rcu_expedited; /* from sysctl */module_param(rcu_expedited, int, 0);extern int rcu_normal; /* from sysctl */module_param(rcu_normal, int, 0);static int rcu_normal_after_boot;module_param(rcu_normal_after_boot, int, 0);#endif /* #ifndef CONFIG_TINY_RCU */ #ifdef CONFIG_DEBUG_LOCK_ALLOC/** * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section? * * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns 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 rcu_idle_enter() and * rcu_idle_exit()) then rcu_read_lock_held() returns 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 SRCU read lock held if the current * CPU is offline. */int rcu_read_lock_sched_held(void){ int lockdep_opinion = 0; if (!debug_lockdep_rcu_enabled()) return 1; if (!rcu_is_watching()) return 0; if (!rcu_lockdep_current_cpu_online()) return 0; if (debug_locks) lockdep_opinion = lock_is_held(&rcu_sched_lock_map); return lockdep_opinion || !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_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) || rcu_scheduler_active == RCU_SCHEDULER_INIT;}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); /* * Inform RCU of the end of the in-kernel boot sequence. */void rcu_end_inkernel_boot(void){ rcu_unexpedite_gp(); if (rcu_normal_after_boot) WRITE_ONCE(rcu_normal, 1);} #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; synchronize_rcu(); synchronize_rcu_expedited();} #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) /* * 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; rcu_test_sync_prims(); return 0;}core_initcall(rcu_set_runtime_mode); #endif /* #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) */ #ifdef CONFIG_DEBUG_LOCK_ALLOCstatic 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); 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); int notrace debug_lockdep_rcu_enabled(void){ return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && debug_locks && current->lockdep_recursion == 0;}EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);NOKPROBE_SYMBOL(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){ if (!debug_lockdep_rcu_enabled()) return 1; if (!rcu_is_watching()) return 0; if (!rcu_lockdep_current_cpu_online()) return 0; 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){ if (!debug_lockdep_rcu_enabled()) return 1; if (!rcu_is_watching()) 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 */ /** * 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, 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; } init_rcu_head_on_stack(&rs_array[i].head); init_completion(&rs_array[i].completion); for (j = 0; j < i; j++) if (crcu_array[j] == crcu_array[i]) break; if (j == i) (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(&rs_array[i].completion); destroy_rcu_head_on_stack(&rs_array[i].head); }}EXPORT_SYMBOL_GPL(__wait_rcu_gp); #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. */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", .is_static_object = rcuhead_is_static_object,};EXPORT_SYMBOL_GPL(rcuhead_debug_descr);#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ #if defined(CONFIG_TREE_RCU) || defined(CONFIG_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_COMMONint rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress);module_param(rcu_cpu_stall_suppress, int, 0644);int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;module_param(rcu_cpu_stall_timeout, int, 0644);#endif /* #ifdef CONFIG_RCU_STALL_COMMON */ #ifdef CONFIG_TASKS_RCU /* * Simple variant of RCU whose quiescent states are voluntary context * switch, cond_resched_rcu_qs(), user-space execution, and idle. * As such, grace periods can take one good long time. There are no * read-side primitives similar to rcu_read_lock() and rcu_read_unlock() * because this implementation is intended to get the system into a safe * state for some of the manipulations involved in tracing and the like. * Finally, this implementation does not support high call_rcu_tasks() * rates from multiple CPUs. If this is required, per-CPU callback lists * will be needed. */ /* Global list of callbacks and associated lock. */static struct rcu_head *rcu_tasks_cbs_head;static struct rcu_head **rcu_tasks_cbs_tail = &rcu_tasks_cbs_head;static DECLARE_WAIT_QUEUE_HEAD(rcu_tasks_cbs_wq);static DEFINE_RAW_SPINLOCK(rcu_tasks_cbs_lock); /* Track exiting tasks in order to allow them to be waited for. */DEFINE_STATIC_SRCU(tasks_rcu_exit_srcu); /* Control stall timeouts. Disable with <= 0, otherwise jiffies till stall. */#define RCU_TASK_STALL_TIMEOUT (HZ * 60 * 10)static int rcu_task_stall_timeout __read_mostly = RCU_TASK_STALL_TIMEOUT;module_param(rcu_task_stall_timeout, int, 0644); static struct task_struct *rcu_tasks_kthread_ptr; /** * call_rcu_tasks() - Queue an RCU for invocation task-based grace period * @rhp: structure to be used for queueing the RCU updates. * @func: actual callback function to be invoked after the grace period * * The callback function will be invoked some time after a full grace * period elapses, in other words after all currently executing RCU * read-side critical sections have completed. call_rcu_tasks() assumes * that the read-side critical sections end at a voluntary context * switch (not a preemption!), cond_resched_rcu_qs(), entry into idle, * or transition to usermode execution. As such, there are no read-side * primitives analogous to rcu_read_lock() and rcu_read_unlock() because * this primitive is intended to determine that all tasks have passed * through a safe state, not so much for data-strcuture synchronization. * * See the description of call_rcu() for more detailed information on * memory ordering guarantees. */void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func){ unsigned long flags; bool needwake; rhp->next = NULL; rhp->func = func; raw_spin_lock_irqsave(&rcu_tasks_cbs_lock, flags); needwake = !rcu_tasks_cbs_head; *rcu_tasks_cbs_tail = rhp; rcu_tasks_cbs_tail = &rhp->next; raw_spin_unlock_irqrestore(&rcu_tasks_cbs_lock, flags); /* We can't create the thread unless interrupts are enabled. */ if (needwake && READ_ONCE(rcu_tasks_kthread_ptr)) wake_up(&rcu_tasks_cbs_wq);}EXPORT_SYMBOL_GPL(call_rcu_tasks); /**Lines 1–500 of 880. 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/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> #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 extern int rcu_expedited; /* from sysctl */ module_param(rcu_expedited, int, 0); extern int rcu_normal; /* from sysctl */ module_param(rcu_normal, int, 0); static int rcu_normal_after_boot; module_param(rcu_normal_after_boot, int, 0); #endif /* #ifndef CONFIG_TINY_RCU */ #ifdef CONFIG_DEBUG_LOCK_ALLOC /** * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section? * * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns 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 rcu_idle_enter() and * rcu_idle_exit()) then rcu_read_lock_held() returns 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 SRCU read lock held if the current * CPU is offline. */ int rcu_read_lock_sched_held(void) { int lockdep_opinion = 0; if (!debug_lockdep_rcu_enabled()) return 1; if (!rcu_is_watching()) return 0; if (!rcu_lockdep_current_cpu_online()) return 0; if (debug_locks) lockdep_opinion = lock_is_held(&rcu_sched_lock_map); return lockdep_opinion || !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_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) || rcu_scheduler_active == RCU_SCHEDULER_INIT; } 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); /* * Inform RCU of the end of the in-kernel boot sequence. */ void rcu_end_inkernel_boot(void) { rcu_unexpedite_gp(); if (rcu_normal_after_boot) WRITE_ONCE(rcu_normal, 1); } #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; synchronize_rcu(); synchronize_rcu_expedited(); } #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) /* * 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; rcu_test_sync_prims(); return 0; } core_initcall(rcu_set_runtime_mode); #endif /* #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) */ #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); 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); int notrace debug_lockdep_rcu_enabled(void) { return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && debug_locks && current->lockdep_recursion == 0; } EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); NOKPROBE_SYMBOL(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) { if (!debug_lockdep_rcu_enabled()) return 1; if (!rcu_is_watching()) return 0; if (!rcu_lockdep_current_cpu_online()) return 0; 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) { if (!debug_lockdep_rcu_enabled()) return 1; if (!rcu_is_watching()) 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 */ /** * 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, 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; } init_rcu_head_on_stack(&rs_array[i].head); init_completion(&rs_array[i].completion); for (j = 0; j < i; j++) if (crcu_array[j] == crcu_array[i]) break; if (j == i) (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(&rs_array[i].completion); destroy_rcu_head_on_stack(&rs_array[i].head); } } EXPORT_SYMBOL_GPL(__wait_rcu_gp); #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. */ 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", .is_static_object = rcuhead_is_static_object, }; EXPORT_SYMBOL_GPL(rcuhead_debug_descr); #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ #if defined(CONFIG_TREE_RCU) || defined(CONFIG_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 int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */ EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress); module_param(rcu_cpu_stall_suppress, int, 0644); int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT; module_param(rcu_cpu_stall_timeout, int, 0644); #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ #ifdef CONFIG_TASKS_RCU /* * Simple variant of RCU whose quiescent states are voluntary context * switch, cond_resched_rcu_qs(), user-space execution, and idle. * As such, grace periods can take one good long time. There are no * read-side primitives similar to rcu_read_lock() and rcu_read_unlock() * because this implementation is intended to get the system into a safe * state for some of the manipulations involved in tracing and the like. * Finally, this implementation does not support high call_rcu_tasks() * rates from multiple CPUs. If this is required, per-CPU callback lists * will be needed. */ /* Global list of callbacks and associated lock. */ static struct rcu_head *rcu_tasks_cbs_head; static struct rcu_head **rcu_tasks_cbs_tail = &rcu_tasks_cbs_head; static DECLARE_WAIT_QUEUE_HEAD(rcu_tasks_cbs_wq); static DEFINE_RAW_SPINLOCK(rcu_tasks_cbs_lock); /* Track exiting tasks in order to allow them to be waited for. */ DEFINE_STATIC_SRCU(tasks_rcu_exit_srcu); /* Control stall timeouts. Disable with <= 0, otherwise jiffies till stall. */ #define RCU_TASK_STALL_TIMEOUT (HZ * 60 * 10) static int rcu_task_stall_timeout __read_mostly = RCU_TASK_STALL_TIMEOUT; module_param(rcu_task_stall_timeout, int, 0644); static struct task_struct *rcu_tasks_kthread_ptr; /** * call_rcu_tasks() - Queue an RCU for invocation task-based grace period * @rhp: structure to be used for queueing the RCU updates. * @func: actual callback function to be invoked after the grace period * * The callback function will be invoked some time after a full grace * period elapses, in other words after all currently executing RCU * read-side critical sections have completed. call_rcu_tasks() assumes * that the read-side critical sections end at a voluntary context * switch (not a preemption!), cond_resched_rcu_qs(), entry into idle, * or transition to usermode execution. As such, there are no read-side * primitives analogous to rcu_read_lock() and rcu_read_unlock() because * this primitive is intended to determine that all tasks have passed * through a safe state, not so much for data-strcuture synchronization. * * See the description of call_rcu() for more detailed information on * memory ordering guarantees. */ void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func) { unsigned long flags; bool needwake; rhp->next = NULL; rhp->func = func; raw_spin_lock_irqsave(&rcu_tasks_cbs_lock, flags); needwake = !rcu_tasks_cbs_head; *rcu_tasks_cbs_tail = rhp; rcu_tasks_cbs_tail = &rhp->next; raw_spin_unlock_irqrestore(&rcu_tasks_cbs_lock, flags); /* We can't create the thread unless interrupts are enabled. */ if (needwake && READ_ONCE(rcu_tasks_kthread_ptr)) wake_up(&rcu_tasks_cbs_wq); } EXPORT_SYMBOL_GPL(call_rcu_tasks); /**