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, write to the Free Software 16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 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/cache.h> 29 30 static inline void rcu_init(void) 31 { 32 } 33 34 static inline void rcu_barrier_bh(void) 35 { 36 wait_rcu_gp(call_rcu_bh); 37 } 38 39 static inline void rcu_barrier_sched(void) 40 { 41 wait_rcu_gp(call_rcu_sched); 42 } 43 44 #ifdef CONFIG_TINY_RCU 45 46 static inline void synchronize_rcu_expedited(void) 47 { 48 synchronize_sched(); /* Only one CPU, so pretty fast anyway!!! */ 49 } 50 51 static inline void rcu_barrier(void) 52 { 53 rcu_barrier_sched(); /* Only one CPU, so only one list of callbacks! */ 54 } 55 56 #else /* #ifdef CONFIG_TINY_RCU */ 57 58 void synchronize_rcu_expedited(void); 59 60 static inline void rcu_barrier(void) 61 { 62 wait_rcu_gp(call_rcu); 63 } 64 65 #endif /* #else #ifdef CONFIG_TINY_RCU */ 66 67 static inline void synchronize_rcu_bh(void) 68 { 69 synchronize_sched(); 70 } 71 72 static inline void synchronize_rcu_bh_expedited(void) 73 { 74 synchronize_sched(); 75 } 76 77 static inline void synchronize_sched_expedited(void) 78 { 79 synchronize_sched(); 80 } 81 82 static inline void kfree_call_rcu(struct rcu_head *head, 83 void (*func)(struct rcu_head *rcu)) 84 { 85 call_rcu(head, func); 86 } 87 88 #ifdef CONFIG_TINY_RCU 89 90 static inline void rcu_preempt_note_context_switch(void) 91 { 92 } 93 94 static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies) 95 { 96 *delta_jiffies = ULONG_MAX; 97 return 0; 98 } 99 100 #else /* #ifdef CONFIG_TINY_RCU */ 101 102 void rcu_preempt_note_context_switch(void); 103 int rcu_preempt_needs_cpu(void); 104 105 static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies) 106 { 107 *delta_jiffies = ULONG_MAX; 108 return rcu_preempt_needs_cpu(); 109 } 110 111 #endif /* #else #ifdef CONFIG_TINY_RCU */ 112 113 static inline void rcu_note_context_switch(int cpu) 114 { 115 rcu_sched_qs(cpu); 116 rcu_preempt_note_context_switch(); 117 } 118 119 /* 120 * Take advantage of the fact that there is only one CPU, which 121 * allows us to ignore virtualization-based context switches. 122 */ 123 static inline void rcu_virt_note_context_switch(int cpu) 124 { 125 } 126 127 /* 128 * Return the number of grace periods. 129 */ 130 static inline long rcu_batches_completed(void) 131 { 132 return 0; 133 } 134 135 /* 136 * Return the number of bottom-half grace periods. 137 */ 138 static inline long rcu_batches_completed_bh(void) 139 { 140 return 0; 141 } 142 143 static inline void rcu_force_quiescent_state(void) 144 { 145 } 146 147 static inline void rcu_bh_force_quiescent_state(void) 148 { 149 } 150 151 static inline void rcu_sched_force_quiescent_state(void) 152 { 153 } 154 155 static inline void rcu_cpu_stall_reset(void) 156 { 157 } 158 159 #ifdef CONFIG_DEBUG_LOCK_ALLOC 160 extern int rcu_scheduler_active __read_mostly; 161 extern void rcu_scheduler_starting(void); 162 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ 163 static inline void rcu_scheduler_starting(void) 164 { 165 } 166 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ 167 168 #endif /* __LINUX_RCUTINY_H */ 169