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