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1 | #ifndef __LINUX_SPINLOCK_UP_H |
2 | #define __LINUX_SPINLOCK_UP_H |
3 | |
4 | #ifndef __LINUX_SPINLOCK_H |
5 | # error "please don't include this file directly" |
6 | #endif |
7 | |
8 | #include <asm/processor.h> /* for cpu_relax() */ |
9 | |
10 | /* |
11 | * include/linux/spinlock_up.h - UP-debug version of spinlocks. |
12 | * |
13 | * portions Copyright 2005, Red Hat, Inc., Ingo Molnar |
14 | * Released under the General Public License (GPL). |
15 | * |
16 | * In the debug case, 1 means unlocked, 0 means locked. (the values |
17 | * are inverted, to catch initialization bugs) |
18 | * |
19 | * No atomicity anywhere, we are on UP. However, we still need |
20 | * the compiler barriers, because we do not want the compiler to |
21 | * move potentially faulting instructions (notably user accesses) |
22 | * into the locked sequence, resulting in non-atomic execution. |
23 | */ |
24 | |
25 | #ifdef CONFIG_DEBUG_SPINLOCK |
26 | #define arch_spin_is_locked(x) ((x)->slock == 0) |
27 | |
28 | static inline void arch_spin_lock(arch_spinlock_t *lock) |
29 | { |
30 | lock->slock = 0; |
31 | barrier(); |
32 | } |
33 | |
34 | static inline void |
35 | arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags) |
36 | { |
37 | local_irq_save(flags); |
38 | lock->slock = 0; |
39 | barrier(); |
40 | } |
41 | |
42 | static inline int arch_spin_trylock(arch_spinlock_t *lock) |
43 | { |
44 | char oldval = lock->slock; |
45 | |
46 | lock->slock = 0; |
47 | barrier(); |
48 | |
49 | return oldval > 0; |
50 | } |
51 | |
52 | static inline void arch_spin_unlock(arch_spinlock_t *lock) |
53 | { |
54 | barrier(); |
55 | lock->slock = 1; |
56 | } |
57 | |
58 | /* |
59 | * Read-write spinlocks. No debug version. |
60 | */ |
61 | #define arch_read_lock(lock) do { barrier(); (void)(lock); } while (0) |
62 | #define arch_write_lock(lock) do { barrier(); (void)(lock); } while (0) |
63 | #define arch_read_trylock(lock) ({ barrier(); (void)(lock); 1; }) |
64 | #define arch_write_trylock(lock) ({ barrier(); (void)(lock); 1; }) |
65 | #define arch_read_unlock(lock) do { barrier(); (void)(lock); } while (0) |
66 | #define arch_write_unlock(lock) do { barrier(); (void)(lock); } while (0) |
67 | |
68 | #else /* DEBUG_SPINLOCK */ |
69 | #define arch_spin_is_locked(lock) ((void)(lock), 0) |
70 | /* for sched/core.c and kernel_lock.c: */ |
71 | # define arch_spin_lock(lock) do { barrier(); (void)(lock); } while (0) |
72 | # define arch_spin_lock_flags(lock, flags) do { barrier(); (void)(lock); } while (0) |
73 | # define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0) |
74 | # define arch_spin_trylock(lock) ({ barrier(); (void)(lock); 1; }) |
75 | #endif /* DEBUG_SPINLOCK */ |
76 | |
77 | #define arch_spin_is_contended(lock) (((void)(lock), 0)) |
78 | |
79 | #define arch_read_can_lock(lock) (((void)(lock), 1)) |
80 | #define arch_write_can_lock(lock) (((void)(lock), 1)) |
81 | |
82 | #define arch_spin_unlock_wait(lock) \ |
83 | do { cpu_relax(); } while (arch_spin_is_locked(lock)) |
84 | |
85 | #endif /* __LINUX_SPINLOCK_UP_H */ |
86 |
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