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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#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 notrace 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 notrace 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 notrace 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 notrace 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. */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);
const 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_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
#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) || IS_ENABLED(CONFIG_LOCK_TORTURE_TEST) || IS_MODULE(CONFIG_LOCK_TORTURE_TEST)/* Get rcutorture access to sched_setaffinity(). */long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask, bool dowarn){ int ret;
ret = sched_setaffinity(pid, in_mask); WARN_ONCE(dowarn && ret, "%s: sched_setaffinity(%d) returned %d\n", __func__, pid, ret); return ret;}EXPORT_SYMBOL_GPL(torture_sched_setaffinity);#endif
#if IS_ENABLED(CONFIG_TRIVIAL_PREEMPT_RCU)// Trivial and stupid grace-period wait. Defined here so that lockdep// kernels can find tasklist_lock.void synchronize_rcu_trivial_preempt(void){ struct task_struct *g; struct task_struct *t;
smp_mb(); // Order prior accesses before grace-period start. rcu_read_lock(); // Protect task list. for_each_process_thread(g, t) { if (t == current) continue; // Don't deadlock on ourselves! // Order later rcu_read_lock() on other tasks after QS. while (smp_load_acquire(&t->rcu_trivial_preempt_nesting)) continue; } rcu_read_unlock();}EXPORT_SYMBOL_GPL(synchronize_rcu_trivial_preempt);#endif // #if IS_ENABLED(CONFIG_TRIVIAL_PREEMPT_RCU)
int rcu_cpu_stall_notifiers __read_mostly; // !0 = provide stall notifiers (rarely useful)EXPORT_SYMBOL_GPL(rcu_cpu_stall_notifiers);
#ifdef CONFIG_RCU_STALL_COMMONint rcu_cpu_stall_ftrace_dump __read_mostly;module_param(rcu_cpu_stall_ftrace_dump, int, 0644);#ifdef CONFIG_RCU_CPU_STALL_NOTIFIERmodule_param(rcu_cpu_stall_notifiers, int, 0444);#endif // #ifdef CONFIG_RCU_CPU_STALL_NOTIFIERint rcu_cpu_stall_suppress __read_mostly; // !0 = 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);int rcu_exp_cpu_stall_timeout __read_mostly = CONFIG_RCU_EXP_CPU_STALL_TIMEOUT;module_param(rcu_exp_cpu_stall_timeout, int, 0644);int rcu_cpu_stall_cputime __read_mostly = IS_ENABLED(CONFIG_RCU_CPU_STALL_CPUTIME);module_param(rcu_cpu_stall_cputime, int, 0644);bool rcu_exp_stall_task_details __read_mostly;module_param(rcu_exp_stall_task_details, bool, 0644);#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
// Suppress boot-time RCU CPU stall warnings and rcutorture writer stall// warnings. Also used by rcutorture even if stall warnings are excluded.int rcu_cpu_stall_suppress_at_boot __read_mostly; // !0 = suppress boot stalls.EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress_at_boot);module_param(rcu_cpu_stall_suppress_at_boot, int, 0444);
/** * get_completed_synchronize_rcu - Return a pre-completed polled state cookie * * Returns a value that will always be treated by functions like * poll_state_synchronize_rcu() as a cookie whose grace period has already * completed. */unsigned long get_completed_synchronize_rcu(void){ return RCU_GET_STATE_COMPLETED;}EXPORT_SYMBOL_GPL(get_completed_synchronize_rcu);
#ifdef CONFIG_PROVE_RCU
/* * Early boot self test parameters. */static bool rcu_self_test;module_param(rcu_self_test, bool, 0444);
static int rcu_self_test_counter;
static void test_callback(struct rcu_head *r){ rcu_self_test_counter++; pr_info("RCU test callback executed %d\n", rcu_self_test_counter);}
DEFINE_STATIC_SRCU(early_srcu);static unsigned long early_srcu_cookie;
struct early_boot_kfree_rcu { struct rcu_head rh;};
static void early_boot_test_call_rcu(void){ static struct rcu_head head; int idx; static struct rcu_head shead; struct early_boot_kfree_rcu *rhp;
idx = srcu_down_read(&early_srcu); srcu_up_read(&early_srcu, idx); call_rcu(&head, test_callback); early_srcu_cookie = start_poll_synchronize_srcu(&early_srcu); call_srcu(&early_srcu, &shead, test_callback); rhp = kmalloc_obj(*rhp); if (!WARN_ON_ONCE(!rhp)) kfree_rcu(rhp, rh);}
void rcu_early_boot_tests(void){ pr_info("Running RCU self tests\n");
if (rcu_self_test) early_boot_test_call_rcu(); rcu_test_sync_prims();}
static int rcu_verify_early_boot_tests(void){ int ret = 0; int early_boot_test_counter = 0;
if (rcu_self_test) { early_boot_test_counter++; rcu_barrier(); early_boot_test_counter++; srcu_barrier(&early_srcu); WARN_ON_ONCE(!poll_state_synchronize_srcu(&early_srcu, early_srcu_cookie)); cleanup_srcu_struct(&early_srcu); } if (rcu_self_test_counter != early_boot_test_counter) { WARN_ON(1); ret = -1; }
return ret;}late_initcall(rcu_verify_early_boot_tests);#elsevoid rcu_early_boot_tests(void) {}#endif /* CONFIG_PROVE_RCU */
#include "tasks.h"
#ifndef CONFIG_TINY_RCU
/* * Print any significant non-default boot-time settings. */void __init rcupdate_announce_bootup_oddness(void){ if (rcu_normal) pr_info("\tNo expedited grace period (rcu_normal).\n"); else if (rcu_normal_after_boot) pr_info("\tNo expedited grace period (rcu_normal_after_boot).\n"); else if (rcu_expedited) pr_info("\tAll grace periods are expedited (rcu_expedited).\n"); if (rcu_cpu_stall_suppress) pr_info("\tRCU CPU stall warnings suppressed (rcu_cpu_stall_suppress).\n"); if (rcu_cpu_stall_timeout != CONFIG_RCU_CPU_STALL_TIMEOUT) pr_info("\tRCU CPU stall warnings timeout set to %d (rcu_cpu_stall_timeout).\n", rcu_cpu_stall_timeout); rcu_tasks_bootup_oddness();}
#endif /* #ifndef CONFIG_TINY_RCU */