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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 | /* * Specialised local-global spinlock. Can only be declared as global variables * to avoid overhead and keep things simple (and we don't want to start using * these inside dynamically allocated structures). * * "local/global locks" (lglocks) can be used to: * * - Provide fast exclusive access to per-CPU data, with exclusive access to * another CPU's data allowed but possibly subject to contention, and to * provide very slow exclusive access to all per-CPU data. * - Or to provide very fast and scalable read serialisation, and to provide * very slow exclusive serialisation of data (not necessarily per-CPU data). * * Brlocks are also implemented as a short-hand notation for the latter use * case. * * Copyright 2009, 2010, Nick Piggin, Novell Inc. */ #ifndef __LINUX_LGLOCK_H #define __LINUX_LGLOCK_H #include <linux/spinlock.h> #include <linux/lockdep.h> #include <linux/percpu.h> #include <linux/cpu.h> /* can make br locks by using local lock for read side, global lock for write */ #define br_lock_init(name) name##_lock_init() #define br_read_lock(name) name##_local_lock() #define br_read_unlock(name) name##_local_unlock() #define br_write_lock(name) name##_global_lock_online() #define br_write_unlock(name) name##_global_unlock_online() #define DECLARE_BRLOCK(name) DECLARE_LGLOCK(name) #define DEFINE_BRLOCK(name) DEFINE_LGLOCK(name) #define lg_lock_init(name) name##_lock_init() #define lg_local_lock(name) name##_local_lock() #define lg_local_unlock(name) name##_local_unlock() #define lg_local_lock_cpu(name, cpu) name##_local_lock_cpu(cpu) #define lg_local_unlock_cpu(name, cpu) name##_local_unlock_cpu(cpu) #define lg_global_lock(name) name##_global_lock() #define lg_global_unlock(name) name##_global_unlock() #define lg_global_lock_online(name) name##_global_lock_online() #define lg_global_unlock_online(name) name##_global_unlock_online() #ifdef CONFIG_DEBUG_LOCK_ALLOC #define LOCKDEP_INIT_MAP lockdep_init_map #define DEFINE_LGLOCK_LOCKDEP(name) \ struct lock_class_key name##_lock_key; \ struct lockdep_map name##_lock_dep_map; \ EXPORT_SYMBOL(name##_lock_dep_map) #else #define LOCKDEP_INIT_MAP(a, b, c, d) #define DEFINE_LGLOCK_LOCKDEP(name) #endif #define DECLARE_LGLOCK(name) \ extern void name##_lock_init(void); \ extern void name##_local_lock(void); \ extern void name##_local_unlock(void); \ extern void name##_local_lock_cpu(int cpu); \ extern void name##_local_unlock_cpu(int cpu); \ extern void name##_global_lock(void); \ extern void name##_global_unlock(void); \ extern void name##_global_lock_online(void); \ extern void name##_global_unlock_online(void); \ #define DEFINE_LGLOCK(name) \ \ DEFINE_SPINLOCK(name##_cpu_lock); \ cpumask_t name##_cpus __read_mostly; \ DEFINE_PER_CPU(arch_spinlock_t, name##_lock); \ DEFINE_LGLOCK_LOCKDEP(name); \ \ static int \ name##_lg_cpu_callback(struct notifier_block *nb, \ unsigned long action, void *hcpu) \ { \ switch (action & ~CPU_TASKS_FROZEN) { \ case CPU_UP_PREPARE: \ spin_lock(&name##_cpu_lock); \ cpu_set((unsigned long)hcpu, name##_cpus); \ spin_unlock(&name##_cpu_lock); \ break; \ case CPU_UP_CANCELED: case CPU_DEAD: \ spin_lock(&name##_cpu_lock); \ cpu_clear((unsigned long)hcpu, name##_cpus); \ spin_unlock(&name##_cpu_lock); \ } \ return NOTIFY_OK; \ } \ static struct notifier_block name##_lg_cpu_notifier = { \ .notifier_call = name##_lg_cpu_callback, \ }; \ void name##_lock_init(void) { \ int i; \ LOCKDEP_INIT_MAP(&name##_lock_dep_map, #name, &name##_lock_key, 0); \ for_each_possible_cpu(i) { \ arch_spinlock_t *lock; \ lock = &per_cpu(name##_lock, i); \ *lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; \ } \ register_hotcpu_notifier(&name##_lg_cpu_notifier); \ get_online_cpus(); \ for_each_online_cpu(i) \ cpu_set(i, name##_cpus); \ put_online_cpus(); \ } \ EXPORT_SYMBOL(name##_lock_init); \ \ void name##_local_lock(void) { \ arch_spinlock_t *lock; \ preempt_disable(); \ rwlock_acquire_read(&name##_lock_dep_map, 0, 0, _THIS_IP_); \ lock = &__get_cpu_var(name##_lock); \ arch_spin_lock(lock); \ } \ EXPORT_SYMBOL(name##_local_lock); \ \ void name##_local_unlock(void) { \ arch_spinlock_t *lock; \ rwlock_release(&name##_lock_dep_map, 1, _THIS_IP_); \ lock = &__get_cpu_var(name##_lock); \ arch_spin_unlock(lock); \ preempt_enable(); \ } \ EXPORT_SYMBOL(name##_local_unlock); \ \ void name##_local_lock_cpu(int cpu) { \ arch_spinlock_t *lock; \ preempt_disable(); \ rwlock_acquire_read(&name##_lock_dep_map, 0, 0, _THIS_IP_); \ lock = &per_cpu(name##_lock, cpu); \ arch_spin_lock(lock); \ } \ EXPORT_SYMBOL(name##_local_lock_cpu); \ \ void name##_local_unlock_cpu(int cpu) { \ arch_spinlock_t *lock; \ rwlock_release(&name##_lock_dep_map, 1, _THIS_IP_); \ lock = &per_cpu(name##_lock, cpu); \ arch_spin_unlock(lock); \ preempt_enable(); \ } \ EXPORT_SYMBOL(name##_local_unlock_cpu); \ \ void name##_global_lock_online(void) { \ int i; \ spin_lock(&name##_cpu_lock); \ rwlock_acquire(&name##_lock_dep_map, 0, 0, _RET_IP_); \ for_each_cpu(i, &name##_cpus) { \ arch_spinlock_t *lock; \ lock = &per_cpu(name##_lock, i); \ arch_spin_lock(lock); \ } \ } \ EXPORT_SYMBOL(name##_global_lock_online); \ \ void name##_global_unlock_online(void) { \ int i; \ rwlock_release(&name##_lock_dep_map, 1, _RET_IP_); \ for_each_cpu(i, &name##_cpus) { \ arch_spinlock_t *lock; \ lock = &per_cpu(name##_lock, i); \ arch_spin_unlock(lock); \ } \ spin_unlock(&name##_cpu_lock); \ } \ EXPORT_SYMBOL(name##_global_unlock_online); \ \ void name##_global_lock(void) { \ int i; \ preempt_disable(); \ rwlock_acquire(&name##_lock_dep_map, 0, 0, _RET_IP_); \ for_each_possible_cpu(i) { \ arch_spinlock_t *lock; \ lock = &per_cpu(name##_lock, i); \ arch_spin_lock(lock); \ } \ } \ EXPORT_SYMBOL(name##_global_lock); \ \ void name##_global_unlock(void) { \ int i; \ rwlock_release(&name##_lock_dep_map, 1, _RET_IP_); \ for_each_possible_cpu(i) { \ arch_spinlock_t *lock; \ lock = &per_cpu(name##_lock, i); \ arch_spin_unlock(lock); \ } \ preempt_enable(); \ } \ EXPORT_SYMBOL(name##_global_unlock); #endif |