1 /* SPDX-License-Identifier: GPL-2.0+ */ 2 /* 3 * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition. 4 * 5 * Copyright IBM Corporation, 2008 6 * 7 * Author: Paul E. McKenney <[email protected]> 8 * 9 * For detailed explanation of Read-Copy Update mechanism see - 10 * Documentation/RCU 11 */ 12 #ifndef __LINUX_TINY_H 13 #define __LINUX_TINY_H 14 15 #include <asm/param.h> /* for HZ */ 16 17 /* Never flag non-existent other CPUs! */ 18 static inline bool rcu_eqs_special_set(int cpu) { return false; } 19 20 static inline unsigned long get_state_synchronize_rcu(void) 21 { 22 return 0; 23 } 24 25 static inline void cond_synchronize_rcu(unsigned long oldstate) 26 { 27 might_sleep(); 28 } 29 30 extern void rcu_barrier(void); 31 32 static inline void synchronize_rcu_expedited(void) 33 { 34 synchronize_rcu(); 35 } 36 37 static inline void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) 38 { 39 call_rcu(head, func); 40 } 41 42 void rcu_qs(void); 43 44 static inline void rcu_softirq_qs(void) 45 { 46 rcu_qs(); 47 } 48 49 #define rcu_note_context_switch(preempt) \ 50 do { \ 51 rcu_qs(); \ 52 rcu_tasks_qs(current); \ 53 } while (0) 54 55 static inline int rcu_needs_cpu(u64 basemono, u64 *nextevt) 56 { 57 *nextevt = KTIME_MAX; 58 return 0; 59 } 60 61 /* 62 * Take advantage of the fact that there is only one CPU, which 63 * allows us to ignore virtualization-based context switches. 64 */ 65 static inline void rcu_virt_note_context_switch(int cpu) { } 66 static inline void rcu_cpu_stall_reset(void) { } 67 static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; } 68 static inline void rcu_idle_enter(void) { } 69 static inline void rcu_idle_exit(void) { } 70 static inline void rcu_irq_enter(void) { } 71 static inline void rcu_irq_exit_irqson(void) { } 72 static inline void rcu_irq_enter_irqson(void) { } 73 static inline void rcu_irq_exit(void) { } 74 static inline void exit_rcu(void) { } 75 static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t) 76 { 77 return false; 78 } 79 static inline void rcu_preempt_deferred_qs(struct task_struct *t) { } 80 #ifdef CONFIG_SRCU 81 void rcu_scheduler_starting(void); 82 #else /* #ifndef CONFIG_SRCU */ 83 static inline void rcu_scheduler_starting(void) { } 84 #endif /* #else #ifndef CONFIG_SRCU */ 85 static inline void rcu_end_inkernel_boot(void) { } 86 static inline bool rcu_inkernel_boot_has_ended(void) { return true; } 87 static inline bool rcu_is_watching(void) { return true; } 88 static inline void rcu_momentary_dyntick_idle(void) { } 89 static inline void kfree_rcu_scheduler_running(void) { } 90 91 /* Avoid RCU read-side critical sections leaking across. */ 92 static inline void rcu_all_qs(void) { barrier(); } 93 94 /* RCUtree hotplug events */ 95 #define rcutree_prepare_cpu NULL 96 #define rcutree_online_cpu NULL 97 #define rcutree_offline_cpu NULL 98 #define rcutree_dead_cpu NULL 99 #define rcutree_dying_cpu NULL 100 static inline void rcu_cpu_starting(unsigned int cpu) { } 101 102 #endif /* __LINUX_RCUTINY_H */ 103