1 #ifndef _PPC64_SEMAPHORE_H
2 #define _PPC64_SEMAPHORE_H
3
4 /*
5 * Remove spinlock-based RW semaphores; RW semaphore definitions are
6 * now in rwsem.h and we use the generic lib/rwsem.c implementation.
7 * Rework semaphores to use atomic_dec_if_positive.
8 * -- Paul Mackerras (paulus@samba.org)
9 */
10
11 #ifdef __KERNEL__
12
13 #include <asm/atomic.h>
14 #include <asm/system.h>
15 #include <linux/wait.h>
16 #include <linux/rwsem.h>
17
18 struct semaphore {
19 /*
20 * Note that any negative value of count is equivalent to 0,
21 * but additionally indicates that some process(es) might be
22 * sleeping on `wait'.
23 */
24 atomic_t count;
25 wait_queue_head_t wait;
26 #if WAITQUEUE_DEBUG
27 long __magic;
28 #endif
29 };
30
31 #if WAITQUEUE_DEBUG
32 # define __SEM_DEBUG_INIT(name) \
33 , (long)&(name).__magic
34 #else
35 # define __SEM_DEBUG_INIT(name)
36 #endif
37
38 #define __SEMAPHORE_INITIALIZER(name, count) \
39 { ATOMIC_INIT(count), \
40 __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
41 __SEM_DEBUG_INIT(name) }
42
43 #define __MUTEX_INITIALIZER(name) \
44 __SEMAPHORE_INITIALIZER(name, 1)
45
46 #define __DECLARE_SEMAPHORE_GENERIC(name, count) \
47 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
48
49 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1)
50 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name, 0)
51
sema_init(struct semaphore * sem,int val)52 static inline void sema_init (struct semaphore *sem, int val)
53 {
54 atomic_set(&sem->count, val);
55 init_waitqueue_head(&sem->wait);
56 #if WAITQUEUE_DEBUG
57 sem->__magic = (long)&sem->__magic;
58 #endif
59 }
60
init_MUTEX(struct semaphore * sem)61 static inline void init_MUTEX (struct semaphore *sem)
62 {
63 sema_init(sem, 1);
64 }
65
init_MUTEX_LOCKED(struct semaphore * sem)66 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
67 {
68 sema_init(sem, 0);
69 }
70
71 extern void __down(struct semaphore * sem);
72 extern int __down_interruptible(struct semaphore * sem);
73 extern void __up(struct semaphore * sem);
74
down(struct semaphore * sem)75 static inline void down(struct semaphore * sem)
76 {
77 #if WAITQUEUE_DEBUG
78 CHECK_MAGIC(sem->__magic);
79 #endif
80
81 /*
82 * Try to get the semaphore, take the slow path if we fail.
83 */
84 if (atomic_dec_return(&sem->count) < 0)
85 __down(sem);
86 smp_wmb();
87 }
88
down_interruptible(struct semaphore * sem)89 static inline int down_interruptible(struct semaphore * sem)
90 {
91 int ret = 0;
92
93 #if WAITQUEUE_DEBUG
94 CHECK_MAGIC(sem->__magic);
95 #endif
96
97 if (atomic_dec_return(&sem->count) < 0)
98 ret = __down_interruptible(sem);
99 smp_wmb();
100 return ret;
101 }
102
down_trylock(struct semaphore * sem)103 static inline int down_trylock(struct semaphore * sem)
104 {
105 int ret;
106
107 #if WAITQUEUE_DEBUG
108 CHECK_MAGIC(sem->__magic);
109 #endif
110
111 ret = atomic_dec_if_positive(&sem->count) < 0;
112 smp_wmb();
113 return ret;
114 }
115
up(struct semaphore * sem)116 static inline void up(struct semaphore * sem)
117 {
118 #if WAITQUEUE_DEBUG
119 CHECK_MAGIC(sem->__magic);
120 #endif
121
122 smp_wmb();
123 if (atomic_inc_return(&sem->count) <= 0)
124 __up(sem);
125 }
126
sem_getcount(struct semaphore * sem)127 static inline int sem_getcount(struct semaphore *sem)
128 {
129 return atomic_read(&sem->count);
130 }
131
132 #endif /* __KERNEL__ */
133
134 #endif /* !(_PPC64_SEMAPHORE_H) */
135