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 <paulmck@linux.ibm.com> 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 struct rcu_gp_oldstate { 18 unsigned long rgos_norm; 19 }; 20 21 // Maximum number of rcu_gp_oldstate values corresponding to 22 // not-yet-completed RCU grace periods. 23 #define NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE 2 24 25 /* 26 * Are the two oldstate values the same? See the Tree RCU version for 27 * docbook header. 28 */ same_state_synchronize_rcu_full(struct rcu_gp_oldstate * rgosp1,struct rcu_gp_oldstate * rgosp2)29static inline bool same_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp1, 30 struct rcu_gp_oldstate *rgosp2) 31 { 32 return rgosp1->rgos_norm == rgosp2->rgos_norm; 33 } 34 35 unsigned long get_state_synchronize_rcu(void); 36 get_state_synchronize_rcu_full(struct rcu_gp_oldstate * rgosp)37static inline void get_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp) 38 { 39 rgosp->rgos_norm = get_state_synchronize_rcu(); 40 } 41 42 unsigned long start_poll_synchronize_rcu(void); 43 start_poll_synchronize_rcu_full(struct rcu_gp_oldstate * rgosp)44static inline void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp) 45 { 46 rgosp->rgos_norm = start_poll_synchronize_rcu(); 47 } 48 49 bool poll_state_synchronize_rcu(unsigned long oldstate); 50 poll_state_synchronize_rcu_full(struct rcu_gp_oldstate * rgosp)51static inline bool poll_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp) 52 { 53 return poll_state_synchronize_rcu(rgosp->rgos_norm); 54 } 55 cond_synchronize_rcu(unsigned long oldstate)56static inline void cond_synchronize_rcu(unsigned long oldstate) 57 { 58 might_sleep(); 59 } 60 cond_synchronize_rcu_full(struct rcu_gp_oldstate * rgosp)61static inline void cond_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp) 62 { 63 cond_synchronize_rcu(rgosp->rgos_norm); 64 } 65 start_poll_synchronize_rcu_expedited(void)66static inline unsigned long start_poll_synchronize_rcu_expedited(void) 67 { 68 return start_poll_synchronize_rcu(); 69 } 70 start_poll_synchronize_rcu_expedited_full(struct rcu_gp_oldstate * rgosp)71static inline void start_poll_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp) 72 { 73 rgosp->rgos_norm = start_poll_synchronize_rcu_expedited(); 74 } 75 cond_synchronize_rcu_expedited(unsigned long oldstate)76static inline void cond_synchronize_rcu_expedited(unsigned long oldstate) 77 { 78 cond_synchronize_rcu(oldstate); 79 } 80 cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate * rgosp)81static inline void cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp) 82 { 83 cond_synchronize_rcu_expedited(rgosp->rgos_norm); 84 } 85 86 extern void rcu_barrier(void); 87 synchronize_rcu_expedited(void)88static inline void synchronize_rcu_expedited(void) 89 { 90 synchronize_rcu(); 91 } 92 93 void rcu_qs(void); 94 rcu_softirq_qs(void)95static inline void rcu_softirq_qs(void) 96 { 97 rcu_qs(); 98 } 99 100 #define rcu_note_context_switch(preempt) \ 101 do { \ 102 rcu_qs(); \ 103 rcu_tasks_qs(current, (preempt)); \ 104 } while (0) 105 rcu_needs_cpu(void)106static inline int rcu_needs_cpu(void) 107 { 108 return 0; 109 } 110 rcu_request_urgent_qs_task(struct task_struct * t)111static inline void rcu_request_urgent_qs_task(struct task_struct *t) { } 112 113 /* 114 * Take advantage of the fact that there is only one CPU, which 115 * allows us to ignore virtualization-based context switches. 116 */ rcu_virt_note_context_switch(void)117static inline void rcu_virt_note_context_switch(void) { } rcu_cpu_stall_reset(void)118static inline void rcu_cpu_stall_reset(void) { } rcu_jiffies_till_stall_check(void)119static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; } rcu_irq_exit_check_preempt(void)120static inline void rcu_irq_exit_check_preempt(void) { } exit_rcu(void)121static inline void exit_rcu(void) { } rcu_preempt_need_deferred_qs(struct task_struct * t)122static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t) 123 { 124 return false; 125 } rcu_preempt_deferred_qs(struct task_struct * t)126static inline void rcu_preempt_deferred_qs(struct task_struct *t) { } 127 void rcu_scheduler_starting(void); rcu_end_inkernel_boot(void)128static inline void rcu_end_inkernel_boot(void) { } rcu_inkernel_boot_has_ended(void)129static inline bool rcu_inkernel_boot_has_ended(void) { return true; } rcu_is_watching(void)130static inline bool rcu_is_watching(void) { return true; } rcu_momentary_eqs(void)131static inline void rcu_momentary_eqs(void) { } 132 133 /* Avoid RCU read-side critical sections leaking across. */ rcu_all_qs(void)134static inline void rcu_all_qs(void) { barrier(); } 135 136 /* RCUtree hotplug events */ 137 #define rcutree_prepare_cpu NULL 138 #define rcutree_online_cpu NULL 139 #define rcutree_offline_cpu NULL 140 #define rcutree_dead_cpu NULL 141 #define rcutree_dying_cpu NULL rcutree_report_cpu_starting(unsigned int cpu)142static inline void rcutree_report_cpu_starting(unsigned int cpu) { } 143 144 #endif /* __LINUX_RCUTINY_H */ 145