locking/lockdep: Remove unused @nested argument from lock_release()
[sfrench/cifs-2.6.git] / include / linux / percpu-rwsem.h
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_PERCPU_RWSEM_H
3 #define _LINUX_PERCPU_RWSEM_H
4
5 #include <linux/atomic.h>
6 #include <linux/rwsem.h>
7 #include <linux/percpu.h>
8 #include <linux/rcuwait.h>
9 #include <linux/rcu_sync.h>
10 #include <linux/lockdep.h>
11
12 struct percpu_rw_semaphore {
13         struct rcu_sync         rss;
14         unsigned int __percpu   *read_count;
15         struct rw_semaphore     rw_sem; /* slowpath */
16         struct rcuwait          writer; /* blocked writer */
17         int                     readers_block;
18 };
19
20 #define __DEFINE_PERCPU_RWSEM(name, is_static)                          \
21 static DEFINE_PER_CPU(unsigned int, __percpu_rwsem_rc_##name);          \
22 is_static struct percpu_rw_semaphore name = {                           \
23         .rss = __RCU_SYNC_INITIALIZER(name.rss),                        \
24         .read_count = &__percpu_rwsem_rc_##name,                        \
25         .rw_sem = __RWSEM_INITIALIZER(name.rw_sem),                     \
26         .writer = __RCUWAIT_INITIALIZER(name.writer),                   \
27 }
28 #define DEFINE_PERCPU_RWSEM(name)               \
29         __DEFINE_PERCPU_RWSEM(name, /* not static */)
30 #define DEFINE_STATIC_PERCPU_RWSEM(name)        \
31         __DEFINE_PERCPU_RWSEM(name, static)
32
33 extern int __percpu_down_read(struct percpu_rw_semaphore *, int);
34 extern void __percpu_up_read(struct percpu_rw_semaphore *);
35
36 static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
37 {
38         might_sleep();
39
40         rwsem_acquire_read(&sem->rw_sem.dep_map, 0, 0, _RET_IP_);
41
42         preempt_disable();
43         /*
44          * We are in an RCU-sched read-side critical section, so the writer
45          * cannot both change sem->state from readers_fast and start checking
46          * counters while we are here. So if we see !sem->state, we know that
47          * the writer won't be checking until we're past the preempt_enable()
48          * and that once the synchronize_rcu() is done, the writer will see
49          * anything we did within this RCU-sched read-size critical section.
50          */
51         __this_cpu_inc(*sem->read_count);
52         if (unlikely(!rcu_sync_is_idle(&sem->rss)))
53                 __percpu_down_read(sem, false); /* Unconditional memory barrier */
54         /*
55          * The preempt_enable() prevents the compiler from
56          * bleeding the critical section out.
57          */
58         preempt_enable();
59 }
60
61 static inline int percpu_down_read_trylock(struct percpu_rw_semaphore *sem)
62 {
63         int ret = 1;
64
65         preempt_disable();
66         /*
67          * Same as in percpu_down_read().
68          */
69         __this_cpu_inc(*sem->read_count);
70         if (unlikely(!rcu_sync_is_idle(&sem->rss)))
71                 ret = __percpu_down_read(sem, true); /* Unconditional memory barrier */
72         preempt_enable();
73         /*
74          * The barrier() from preempt_enable() prevents the compiler from
75          * bleeding the critical section out.
76          */
77
78         if (ret)
79                 rwsem_acquire_read(&sem->rw_sem.dep_map, 0, 1, _RET_IP_);
80
81         return ret;
82 }
83
84 static inline void percpu_up_read(struct percpu_rw_semaphore *sem)
85 {
86         preempt_disable();
87         /*
88          * Same as in percpu_down_read().
89          */
90         if (likely(rcu_sync_is_idle(&sem->rss)))
91                 __this_cpu_dec(*sem->read_count);
92         else
93                 __percpu_up_read(sem); /* Unconditional memory barrier */
94         preempt_enable();
95
96         rwsem_release(&sem->rw_sem.dep_map, _RET_IP_);
97 }
98
99 extern void percpu_down_write(struct percpu_rw_semaphore *);
100 extern void percpu_up_write(struct percpu_rw_semaphore *);
101
102 extern int __percpu_init_rwsem(struct percpu_rw_semaphore *,
103                                 const char *, struct lock_class_key *);
104
105 extern void percpu_free_rwsem(struct percpu_rw_semaphore *);
106
107 #define percpu_init_rwsem(sem)                                  \
108 ({                                                              \
109         static struct lock_class_key rwsem_key;                 \
110         __percpu_init_rwsem(sem, #sem, &rwsem_key);             \
111 })
112
113 #define percpu_rwsem_is_held(sem) lockdep_is_held(&(sem)->rw_sem)
114
115 #define percpu_rwsem_assert_held(sem)                           \
116         lockdep_assert_held(&(sem)->rw_sem)
117
118 static inline void percpu_rwsem_release(struct percpu_rw_semaphore *sem,
119                                         bool read, unsigned long ip)
120 {
121         lock_release(&sem->rw_sem.dep_map, ip);
122 #ifdef CONFIG_RWSEM_SPIN_ON_OWNER
123         if (!read)
124                 atomic_long_set(&sem->rw_sem.owner, RWSEM_OWNER_UNKNOWN);
125 #endif
126 }
127
128 static inline void percpu_rwsem_acquire(struct percpu_rw_semaphore *sem,
129                                         bool read, unsigned long ip)
130 {
131         lock_acquire(&sem->rw_sem.dep_map, 0, 1, read, 1, NULL, ip);
132 #ifdef CONFIG_RWSEM_SPIN_ON_OWNER
133         if (!read)
134                 atomic_long_set(&sem->rw_sem.owner, (long)current);
135 #endif
136 }
137
138 #endif