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Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
[karo-tx-linux.git] / include / linux / spinlock_up.h
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 #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_unlock_wait(arch_spinlock_t *lock)
30 {
31         smp_cond_load_acquire(&lock->slock, VAL);
32 }
33
34 static inline void arch_spin_lock(arch_spinlock_t *lock)
35 {
36         lock->slock = 0;
37         barrier();
38 }
39
40 static inline void
41 arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
42 {
43         local_irq_save(flags);
44         lock->slock = 0;
45         barrier();
46 }
47
48 static inline int arch_spin_trylock(arch_spinlock_t *lock)
49 {
50         char oldval = lock->slock;
51
52         lock->slock = 0;
53         barrier();
54
55         return oldval > 0;
56 }
57
58 static inline void arch_spin_unlock(arch_spinlock_t *lock)
59 {
60         barrier();
61         lock->slock = 1;
62 }
63
64 /*
65  * Read-write spinlocks. No debug version.
66  */
67 #define arch_read_lock(lock)            do { barrier(); (void)(lock); } while (0)
68 #define arch_write_lock(lock)           do { barrier(); (void)(lock); } while (0)
69 #define arch_read_trylock(lock) ({ barrier(); (void)(lock); 1; })
70 #define arch_write_trylock(lock)        ({ barrier(); (void)(lock); 1; })
71 #define arch_read_unlock(lock)          do { barrier(); (void)(lock); } while (0)
72 #define arch_write_unlock(lock) do { barrier(); (void)(lock); } while (0)
73
74 #else /* DEBUG_SPINLOCK */
75 #define arch_spin_is_locked(lock)       ((void)(lock), 0)
76 #define arch_spin_unlock_wait(lock)     do { barrier(); (void)(lock); } while (0)
77 /* for sched/core.c and kernel_lock.c: */
78 # define arch_spin_lock(lock)           do { barrier(); (void)(lock); } while (0)
79 # define arch_spin_lock_flags(lock, flags)      do { barrier(); (void)(lock); } while (0)
80 # define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0)
81 # define arch_spin_trylock(lock)        ({ barrier(); (void)(lock); 1; })
82 #endif /* DEBUG_SPINLOCK */
83
84 #define arch_spin_is_contended(lock)    (((void)(lock), 0))
85
86 #define arch_read_can_lock(lock)        (((void)(lock), 1))
87 #define arch_write_can_lock(lock)       (((void)(lock), 1))
88
89 #endif /* __LINUX_SPINLOCK_UP_H */