1 #ifndef ASMARM_SEMAPHORE_HELPER_H
2 #define ASMARM_SEMAPHORE_HELPER_H
3
4 /*
5 * These two _must_ execute atomically wrt each other.
6 */
7 static inline void wake_one_more(struct semaphore * sem)
8 {
9 unsigned long flags;
10
11 spin_lock_irqsave(&semaphore_wake_lock, flags);
12 if (atomic_read(&sem->count) <= 0)
13 sem->waking++;
14 spin_unlock_irqrestore(&semaphore_wake_lock, flags);
15 }
16
17 static inline int waking_non_zero(struct semaphore *sem)
18 {
19 unsigned long flags;
20 int ret = 0;
21
22 spin_lock_irqsave(&semaphore_wake_lock, flags);
23 if (sem->waking > 0) {
24 sem->waking--;
25 ret = 1;
26 }
27 spin_unlock_irqrestore(&semaphore_wake_lock, flags);
28 return ret;
29 }
30
31 /*
32 * waking non zero interruptible
33 * 1 got the lock
34 * 0 go to sleep
35 * -EINTR interrupted
36 *
37 * We must undo the sem->count down_interruptible() increment while we are
38 * protected by the spinlock in order to make this atomic_inc() with the
39 * atomic_read() in wake_one_more(), otherwise we can race. -arca
40 */
41 static inline int waking_non_zero_interruptible(struct semaphore *sem,
42 struct task_struct *tsk)
43 {
44 unsigned long flags;
45 int ret = 0;
46
47 spin_lock_irqsave(&semaphore_wake_lock, flags);
48 if (sem->waking > 0) {
49 sem->waking--;
50 ret = 1;
51 } else if (signal_pending(tsk)) {
52 atomic_inc(&sem->count);
53 ret = -EINTR;
54 }
55 spin_unlock_irqrestore(&semaphore_wake_lock, flags);
56 return ret;
57 }
58
59 /*
60 * waking_non_zero_try_lock:
61 * 1 failed to lock
62 * 0 got the lock
63 *
64 * We must undo the sem->count down_interruptible() increment while we are
65 * protected by the spinlock in order to make this atomic_inc() with the
66 * atomic_read() in wake_one_more(), otherwise we can race. -arca
67 */
68 static inline int waking_non_zero_trylock(struct semaphore *sem)
69 {
70 unsigned long flags;
71 int ret = 1;
72
73 spin_lock_irqsave(&semaphore_wake_lock, flags);
74 if (sem->waking <= 0)
75 atomic_inc(&sem->count);
76 else {
77 sem->waking--;
78 ret = 0;
79 }
80 spin_unlock_irqrestore(&semaphore_wake_lock, flags);
81 return ret;
82 }
83
84 #endif
85
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