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