1 /* 2 * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition. 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, you can access it online at 16 * http://www.gnu.org/licenses/gpl-2.0.html. 17 * 18 * Copyright IBM Corporation, 2008 19 * 20 * Author: Paul E. McKenney <[email protected]> 21 * 22 * For detailed explanation of Read-Copy Update mechanism see - 23 * Documentation/RCU 24 */ 25 #ifndef __LINUX_TINY_H 26 #define __LINUX_TINY_H 27 28 #include <linux/ktime.h> 29 30 /* Never flag non-existent other CPUs! */ 31 static inline bool rcu_eqs_special_set(int cpu) { return false; } 32 33 static inline unsigned long get_state_synchronize_rcu(void) 34 { 35 return 0; 36 } 37 38 static inline void cond_synchronize_rcu(unsigned long oldstate) 39 { 40 might_sleep(); 41 } 42 43 extern void rcu_barrier(void); 44 45 static inline void synchronize_rcu_expedited(void) 46 { 47 synchronize_rcu(); 48 } 49 50 static inline void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) 51 { 52 call_rcu(head, func); 53 } 54 55 void rcu_qs(void); 56 57 static inline void rcu_softirq_qs(void) 58 { 59 rcu_qs(); 60 } 61 62 #define rcu_note_context_switch(preempt) \ 63 do { \ 64 rcu_qs(); \ 65 rcu_tasks_qs(current); \ 66 } while (0) 67 68 static inline int rcu_needs_cpu(u64 basemono, u64 *nextevt) 69 { 70 *nextevt = KTIME_MAX; 71 return 0; 72 } 73 74 /* 75 * Take advantage of the fact that there is only one CPU, which 76 * allows us to ignore virtualization-based context switches. 77 */ 78 static inline void rcu_virt_note_context_switch(int cpu) { } 79 static inline void rcu_cpu_stall_reset(void) { } 80 static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; } 81 static inline void rcu_idle_enter(void) { } 82 static inline void rcu_idle_exit(void) { } 83 static inline void rcu_irq_enter(void) { } 84 static inline void rcu_irq_exit_irqson(void) { } 85 static inline void rcu_irq_enter_irqson(void) { } 86 static inline void rcu_irq_exit(void) { } 87 static inline void exit_rcu(void) { } 88 static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t) 89 { 90 return false; 91 } 92 static inline void rcu_preempt_deferred_qs(struct task_struct *t) { } 93 #ifdef CONFIG_SRCU 94 void rcu_scheduler_starting(void); 95 #else /* #ifndef CONFIG_SRCU */ 96 static inline void rcu_scheduler_starting(void) { } 97 #endif /* #else #ifndef CONFIG_SRCU */ 98 static inline void rcu_end_inkernel_boot(void) { } 99 static inline bool rcu_is_watching(void) { return true; } 100 101 /* Avoid RCU read-side critical sections leaking across. */ 102 static inline void rcu_all_qs(void) { barrier(); } 103 104 /* RCUtree hotplug events */ 105 #define rcutree_prepare_cpu NULL 106 #define rcutree_online_cpu NULL 107 #define rcutree_offline_cpu NULL 108 #define rcutree_dead_cpu NULL 109 #define rcutree_dying_cpu NULL 110 static inline void rcu_cpu_starting(unsigned int cpu) { } 111 112 #endif /* __LINUX_RCUTINY_H */ 113