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 /* Never flag non-existent other CPUs! */ 18 static inline bool rcu_eqs_special_set(int cpu) { return false; } 19 20 unsigned long get_state_synchronize_rcu(void); 21 unsigned long start_poll_synchronize_rcu(void); 22 bool poll_state_synchronize_rcu(unsigned long oldstate); 23 24 static inline void cond_synchronize_rcu(unsigned long oldstate) 25 { 26 might_sleep(); 27 } 28 29 extern void rcu_barrier(void); 30 31 static inline void synchronize_rcu_expedited(void) 32 { 33 synchronize_rcu(); 34 } 35 36 /* 37 * Add one more declaration of kvfree() here. It is 38 * not so straight forward to just include <linux/mm.h> 39 * where it is defined due to getting many compile 40 * errors caused by that include. 41 */ 42 extern void kvfree(const void *addr); 43 44 static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) 45 { 46 if (head) { 47 call_rcu(head, func); 48 return; 49 } 50 51 // kvfree_rcu(one_arg) call. 52 might_sleep(); 53 synchronize_rcu(); 54 kvfree((void *) func); 55 } 56 57 void rcu_qs(void); 58 59 static inline void rcu_softirq_qs(void) 60 { 61 rcu_qs(); 62 } 63 64 #define rcu_note_context_switch(preempt) \ 65 do { \ 66 rcu_qs(); \ 67 rcu_tasks_qs(current, (preempt)); \ 68 } while (0) 69 70 static inline int rcu_needs_cpu(u64 basemono, u64 *nextevt) 71 { 72 *nextevt = KTIME_MAX; 73 return 0; 74 } 75 76 /* 77 * Take advantage of the fact that there is only one CPU, which 78 * allows us to ignore virtualization-based context switches. 79 */ 80 static inline void rcu_virt_note_context_switch(int cpu) { } 81 static inline void rcu_cpu_stall_reset(void) { } 82 static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; } 83 static inline void rcu_idle_enter(void) { } 84 static inline void rcu_idle_exit(void) { } 85 static inline void rcu_irq_enter(void) { } 86 static inline void rcu_irq_exit_irqson(void) { } 87 static inline void rcu_irq_enter_irqson(void) { } 88 static inline void rcu_irq_exit(void) { } 89 static inline void rcu_irq_exit_check_preempt(void) { } 90 #define rcu_is_idle_cpu(cpu) \ 91 (is_idle_task(current) && !in_nmi() && !in_irq() && !in_serving_softirq()) 92 static inline void exit_rcu(void) { } 93 static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t) 94 { 95 return false; 96 } 97 static inline void rcu_preempt_deferred_qs(struct task_struct *t) { } 98 #ifdef CONFIG_SRCU 99 void rcu_scheduler_starting(void); 100 #else /* #ifndef CONFIG_SRCU */ 101 static inline void rcu_scheduler_starting(void) { } 102 #endif /* #else #ifndef CONFIG_SRCU */ 103 static inline void rcu_end_inkernel_boot(void) { } 104 static inline bool rcu_inkernel_boot_has_ended(void) { return true; } 105 static inline bool rcu_is_watching(void) { return true; } 106 static inline void rcu_momentary_dyntick_idle(void) { } 107 static inline void kfree_rcu_scheduler_running(void) { } 108 static inline bool rcu_gp_might_be_stalled(void) { return false; } 109 110 /* Avoid RCU read-side critical sections leaking across. */ 111 static inline void rcu_all_qs(void) { barrier(); } 112 113 /* RCUtree hotplug events */ 114 #define rcutree_prepare_cpu NULL 115 #define rcutree_online_cpu NULL 116 #define rcutree_offline_cpu NULL 117 #define rcutree_dead_cpu NULL 118 #define rcutree_dying_cpu NULL 119 static inline void rcu_cpu_starting(unsigned int cpu) { } 120 121 #endif /* __LINUX_RCUTINY_H */ 122