| blob | 87f402ccec55567330943ab774ffb12ae21c7da8 |
1 /*
2 * Specialised local-global spinlock. Can only be declared as global variables
3 * to avoid overhead and keep things simple (and we don't want to start using
4 * these inside dynamically allocated structures).
5 *
6 * "local/global locks" (lglocks) can be used to:
7 *
8 * - Provide fast exclusive access to per-CPU data, with exclusive access to
9 * another CPU's data allowed but possibly subject to contention, and to
10 * provide very slow exclusive access to all per-CPU data.
11 * - Or to provide very fast and scalable read serialisation, and to provide
12 * very slow exclusive serialisation of data (not necessarily per-CPU data).
13 *
14 * Brlocks are also implemented as a short-hand notation for the latter use
15 * case.
16 *
17 * Copyright 2009, 2010, Nick Piggin, Novell Inc.
18 */
19 #ifndef __LINUX_LGLOCK_H
20 #define __LINUX_LGLOCK_H
22 #include <linux/spinlock.h>
23 #include <linux/lockdep.h>
24 #include <linux/percpu.h>
25 #include <linux/cpu.h>
27 /* can make br locks by using local lock for read side, global lock for write */
28 #define br_lock_init(name) name##_lock_init()
29 #define br_read_lock(name) name##_local_lock()
30 #define br_read_unlock(name) name##_local_unlock()
31 #define br_write_lock(name) name##_global_lock_online()
32 #define br_write_unlock(name) name##_global_unlock_online()
34 #define DECLARE_BRLOCK(name) DECLARE_LGLOCK(name)
35 #define DEFINE_BRLOCK(name) DEFINE_LGLOCK(name)
38 #define lg_lock_init(name) name##_lock_init()
39 #define lg_local_lock(name) name##_local_lock()
40 #define lg_local_unlock(name) name##_local_unlock()
41 #define lg_local_lock_cpu(name, cpu) name##_local_lock_cpu(cpu)
42 #define lg_local_unlock_cpu(name, cpu) name##_local_unlock_cpu(cpu)
43 #define lg_global_lock(name) name##_global_lock()
44 #define lg_global_unlock(name) name##_global_unlock()
45 #define lg_global_lock_online(name) name##_global_lock_online()
46 #define lg_global_unlock_online(name) name##_global_unlock_online()
48 #ifdef CONFIG_DEBUG_LOCK_ALLOC
49 #define LOCKDEP_INIT_MAP lockdep_init_map
51 #define DEFINE_LGLOCK_LOCKDEP(name) \
52 struct lock_class_key name##_lock_key; \
53 struct lockdep_map name##_lock_dep_map; \
54 EXPORT_SYMBOL(name##_lock_dep_map)
56 #else
57 #define LOCKDEP_INIT_MAP(a, b, c, d)
59 #define DEFINE_LGLOCK_LOCKDEP(name)
60 #endif
63 #define DECLARE_LGLOCK(name) \
64 extern void name##_lock_init(void); \
65 extern void name##_local_lock(void); \
66 extern void name##_local_unlock(void); \
67 extern void name##_local_lock_cpu(int cpu); \
68 extern void name##_local_unlock_cpu(int cpu); \
69 extern void name##_global_lock(void); \
70 extern void name##_global_unlock(void); \
71 extern void name##_global_lock_online(void); \
72 extern void name##_global_unlock_online(void); \
74 #define DEFINE_LGLOCK(name) \
75 \
76 DEFINE_SPINLOCK(name##_cpu_lock); \
77 cpumask_t name##_cpus __read_mostly; \
78 DEFINE_PER_CPU(arch_spinlock_t, name##_lock); \
79 DEFINE_LGLOCK_LOCKDEP(name); \
80 \
81 static int \
82 name##_lg_cpu_callback(struct notifier_block *nb, \
83 unsigned long action, void *hcpu) \
84 { \
85 switch (action & ~CPU_TASKS_FROZEN) { \
86 case CPU_UP_PREPARE: \
87 spin_lock(&name##_cpu_lock); \
88 cpu_set((unsigned long)hcpu, name##_cpus); \
89 spin_unlock(&name##_cpu_lock); \
90 break; \
91 case CPU_UP_CANCELED: case CPU_DEAD: \
92 spin_lock(&name##_cpu_lock); \
93 cpu_clear((unsigned long)hcpu, name##_cpus); \
94 spin_unlock(&name##_cpu_lock); \
95 } \
96 return NOTIFY_OK; \
97 } \
98 static struct notifier_block name##_lg_cpu_notifier = { \
99 .notifier_call = name##_lg_cpu_callback, \
100 }; \
101 void name##_lock_init(void) { \
102 int i; \
103 LOCKDEP_INIT_MAP(&name##_lock_dep_map, #name, &name##_lock_key, 0); \
104 for_each_possible_cpu(i) { \
105 arch_spinlock_t *lock; \
106 lock = &per_cpu(name##_lock, i); \
107 *lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; \
108 } \
109 register_hotcpu_notifier(&name##_lg_cpu_notifier); \
110 get_online_cpus(); \
111 for_each_online_cpu(i) \
112 cpu_set(i, name##_cpus); \
113 put_online_cpus(); \
114 } \
115 EXPORT_SYMBOL(name##_lock_init); \
116 \
117 void name##_local_lock(void) { \
118 arch_spinlock_t *lock; \
119 preempt_disable(); \
120 rwlock_acquire_read(&name##_lock_dep_map, 0, 0, _THIS_IP_); \
121 lock = &__get_cpu_var(name##_lock); \
122 arch_spin_lock(lock); \
123 } \
124 EXPORT_SYMBOL(name##_local_lock); \
125 \
126 void name##_local_unlock(void) { \
127 arch_spinlock_t *lock; \
128 rwlock_release(&name##_lock_dep_map, 1, _THIS_IP_); \
129 lock = &__get_cpu_var(name##_lock); \
130 arch_spin_unlock(lock); \
131 preempt_enable(); \
132 } \
133 EXPORT_SYMBOL(name##_local_unlock); \
134 \
135 void name##_local_lock_cpu(int cpu) { \
136 arch_spinlock_t *lock; \
137 preempt_disable(); \
138 rwlock_acquire_read(&name##_lock_dep_map, 0, 0, _THIS_IP_); \
139 lock = &per_cpu(name##_lock, cpu); \
140 arch_spin_lock(lock); \
141 } \
142 EXPORT_SYMBOL(name##_local_lock_cpu); \
143 \
144 void name##_local_unlock_cpu(int cpu) { \
145 arch_spinlock_t *lock; \
146 rwlock_release(&name##_lock_dep_map, 1, _THIS_IP_); \
147 lock = &per_cpu(name##_lock, cpu); \
148 arch_spin_unlock(lock); \
149 preempt_enable(); \
150 } \
151 EXPORT_SYMBOL(name##_local_unlock_cpu); \
152 \
153 void name##_global_lock_online(void) { \
154 int i; \
155 spin_lock(&name##_cpu_lock); \
156 rwlock_acquire(&name##_lock_dep_map, 0, 0, _RET_IP_); \
157 for_each_cpu(i, &name##_cpus) { \
158 arch_spinlock_t *lock; \
159 lock = &per_cpu(name##_lock, i); \
160 arch_spin_lock(lock); \
161 } \
162 } \
163 EXPORT_SYMBOL(name##_global_lock_online); \
164 \
165 void name##_global_unlock_online(void) { \
166 int i; \
167 rwlock_release(&name##_lock_dep_map, 1, _RET_IP_); \
168 for_each_cpu(i, &name##_cpus) { \
169 arch_spinlock_t *lock; \
170 lock = &per_cpu(name##_lock, i); \
171 arch_spin_unlock(lock); \
172 } \
173 spin_unlock(&name##_cpu_lock); \
174 } \
175 EXPORT_SYMBOL(name##_global_unlock_online); \
176 \
177 void name##_global_lock(void) { \
178 int i; \
179 preempt_disable(); \
180 rwlock_acquire(&name##_lock_dep_map, 0, 0, _RET_IP_); \
181 for_each_possible_cpu(i) { \
182 arch_spinlock_t *lock; \
183 lock = &per_cpu(name##_lock, i); \
184 arch_spin_lock(lock); \
185 } \
186 } \
187 EXPORT_SYMBOL(name##_global_lock); \
188 \
189 void name##_global_unlock(void) { \
190 int i; \
191 rwlock_release(&name##_lock_dep_map, 1, _RET_IP_); \
192 for_each_possible_cpu(i) { \
193 arch_spinlock_t *lock; \
194 lock = &per_cpu(name##_lock, i); \
195 arch_spin_unlock(lock); \
196 } \
197 preempt_enable(); \
198 } \
199 EXPORT_SYMBOL(name##_global_unlock);
200 #endif