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 unsigned long get_state_synchronize_rcu(void); 18 unsigned long start_poll_synchronize_rcu(void); 19 bool poll_state_synchronize_rcu(unsigned long oldstate); 20 21 static inline void cond_synchronize_rcu(unsigned long oldstate) 22 { 23 might_sleep(); 24 } 25 26 static inline unsigned long start_poll_synchronize_rcu_expedited(void) 27 { 28 return start_poll_synchronize_rcu(); 29 } 30 31 static inline void cond_synchronize_rcu_expedited(unsigned long oldstate) 32 { 33 cond_synchronize_rcu(oldstate); 34 } 35 36 extern void rcu_barrier(void); 37 38 static inline void synchronize_rcu_expedited(void) 39 { 40 synchronize_rcu(); 41 } 42 43 /* 44 * Add one more declaration of kvfree() here. It is 45 * not so straight forward to just include <linux/mm.h> 46 * where it is defined due to getting many compile 47 * errors caused by that include. 48 */ 49 extern void kvfree(const void *addr); 50 51 static inline void __kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) 52 { 53 if (head) { 54 call_rcu(head, func); 55 return; 56 } 57 58 // kvfree_rcu(one_arg) call. 59 might_sleep(); 60 synchronize_rcu(); 61 kvfree((void *) func); 62 } 63 64 #ifdef CONFIG_KASAN_GENERIC 65 void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func); 66 #else 67 static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) 68 { 69 __kvfree_call_rcu(head, func); 70 } 71 #endif 72 73 void rcu_qs(void); 74 75 static inline void rcu_softirq_qs(void) 76 { 77 rcu_qs(); 78 } 79 80 #define rcu_note_context_switch(preempt) \ 81 do { \ 82 rcu_qs(); \ 83 rcu_tasks_qs(current, (preempt)); \ 84 } while (0) 85 86 static inline int rcu_needs_cpu(void) 87 { 88 return 0; 89 } 90 91 /* 92 * Take advantage of the fact that there is only one CPU, which 93 * allows us to ignore virtualization-based context switches. 94 */ 95 static inline void rcu_virt_note_context_switch(int cpu) { } 96 static inline void rcu_cpu_stall_reset(void) { } 97 static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; } 98 static inline void rcu_irq_exit_check_preempt(void) { } 99 #define rcu_is_idle_cpu(cpu) \ 100 (is_idle_task(current) && !in_nmi() && !in_hardirq() && !in_serving_softirq()) 101 static inline void exit_rcu(void) { } 102 static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t) 103 { 104 return false; 105 } 106 static inline void rcu_preempt_deferred_qs(struct task_struct *t) { } 107 #ifdef CONFIG_SRCU 108 void rcu_scheduler_starting(void); 109 #else /* #ifndef CONFIG_SRCU */ 110 static inline void rcu_scheduler_starting(void) { } 111 #endif /* #else #ifndef CONFIG_SRCU */ 112 static inline void rcu_end_inkernel_boot(void) { } 113 static inline bool rcu_inkernel_boot_has_ended(void) { return true; } 114 static inline bool rcu_is_watching(void) { return true; } 115 static inline void rcu_momentary_dyntick_idle(void) { } 116 static inline void kfree_rcu_scheduler_running(void) { } 117 static inline bool rcu_gp_might_be_stalled(void) { return false; } 118 119 /* Avoid RCU read-side critical sections leaking across. */ 120 static inline void rcu_all_qs(void) { barrier(); } 121 122 /* RCUtree hotplug events */ 123 #define rcutree_prepare_cpu NULL 124 #define rcutree_online_cpu NULL 125 #define rcutree_offline_cpu NULL 126 #define rcutree_dead_cpu NULL 127 #define rcutree_dying_cpu NULL 128 static inline void rcu_cpu_starting(unsigned int cpu) { } 129 130 #endif /* __LINUX_RCUTINY_H */ 131