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1da177e4 LT |
1 | #ifndef __ASM_SH_SEMAPHORE_HELPER_H |
2 | #define __ASM_SH_SEMAPHORE_HELPER_H | |
3 | ||
4 | /* | |
5 | * SMP- and interrupt-safe semaphores helper functions. | |
6 | * | |
7 | * (C) Copyright 1996 Linus Torvalds | |
8 | * (C) Copyright 1999 Andrea Arcangeli | |
9 | */ | |
10 | ||
11 | /* | |
12 | * These two _must_ execute atomically wrt each other. | |
13 | * | |
14 | * This is trivially done with load_locked/store_cond, | |
15 | * which we have. Let the rest of the losers suck eggs. | |
16 | */ | |
17 | static __inline__ void wake_one_more(struct semaphore * sem) | |
18 | { | |
19 | atomic_inc((atomic_t *)&sem->sleepers); | |
20 | } | |
21 | ||
22 | static __inline__ int waking_non_zero(struct semaphore *sem) | |
23 | { | |
24 | unsigned long flags; | |
25 | int ret = 0; | |
26 | ||
27 | spin_lock_irqsave(&semaphore_wake_lock, flags); | |
28 | if (sem->sleepers > 0) { | |
29 | sem->sleepers--; | |
30 | ret = 1; | |
31 | } | |
32 | spin_unlock_irqrestore(&semaphore_wake_lock, flags); | |
33 | return ret; | |
34 | } | |
35 | ||
36 | /* | |
37 | * waking_non_zero_interruptible: | |
38 | * 1 got the lock | |
39 | * 0 go to sleep | |
40 | * -EINTR interrupted | |
41 | * | |
42 | * We must undo the sem->count down_interruptible() increment while we are | |
43 | * protected by the spinlock in order to make atomic this atomic_inc() with the | |
44 | * atomic_read() in wake_one_more(), otherwise we can race. -arca | |
45 | */ | |
46 | static __inline__ int waking_non_zero_interruptible(struct semaphore *sem, | |
47 | struct task_struct *tsk) | |
48 | { | |
49 | unsigned long flags; | |
50 | int ret = 0; | |
51 | ||
52 | spin_lock_irqsave(&semaphore_wake_lock, flags); | |
53 | if (sem->sleepers > 0) { | |
54 | sem->sleepers--; | |
55 | ret = 1; | |
56 | } else if (signal_pending(tsk)) { | |
57 | atomic_inc(&sem->count); | |
58 | ret = -EINTR; | |
59 | } | |
60 | spin_unlock_irqrestore(&semaphore_wake_lock, flags); | |
61 | return ret; | |
62 | } | |
63 | ||
64 | /* | |
65 | * waking_non_zero_trylock: | |
66 | * 1 failed to lock | |
67 | * 0 got the lock | |
68 | * | |
69 | * We must undo the sem->count down_trylock() increment while we are | |
70 | * protected by the spinlock in order to make atomic this atomic_inc() with the | |
71 | * atomic_read() in wake_one_more(), otherwise we can race. -arca | |
72 | */ | |
73 | static __inline__ int waking_non_zero_trylock(struct semaphore *sem) | |
74 | { | |
75 | unsigned long flags; | |
76 | int ret = 1; | |
77 | ||
78 | spin_lock_irqsave(&semaphore_wake_lock, flags); | |
79 | if (sem->sleepers <= 0) | |
80 | atomic_inc(&sem->count); | |
81 | else { | |
82 | sem->sleepers--; | |
83 | ret = 0; | |
84 | } | |
85 | spin_unlock_irqrestore(&semaphore_wake_lock, flags); | |
86 | return ret; | |
87 | } | |
88 | ||
89 | #endif /* __ASM_SH_SEMAPHORE_HELPER_H */ |