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1da177e4 LT |
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 |