Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#ifndef __LINUX_SPINLOCK_UP_H
2#define __LINUX_SPINLOCK_UP_H
3
4#ifndef __LINUX_INSIDE_SPINLOCK_H
5# error "Please do not 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
29static inline void arch_spin_lock(arch_spinlock_t *lock)
30{
31 lock->slock = 0;
32 barrier();
33}
34
35static 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
45static inline void arch_spin_unlock(arch_spinlock_t *lock)
46{
47 barrier();
48 lock->slock = 1;
49}
50
51#else /* DEBUG_SPINLOCK */
52#define arch_spin_is_locked(lock) ((void)(lock), 0)
53/* for sched/core.c and kernel_lock.c: */
54# define arch_spin_lock(lock) do { barrier(); (void)(lock); } while (0)
55# define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0)
56# define arch_spin_trylock(lock) ({ barrier(); (void)(lock); 1; })
57#endif /* DEBUG_SPINLOCK */
58
59#define arch_spin_is_contended(lock) (((void)(lock), 0))
60
61/*
62 * Read-write spinlocks. No debug version.
63 */
64#define arch_read_lock(lock) do { barrier(); (void)(lock); } while (0)
65#define arch_write_lock(lock) do { barrier(); (void)(lock); } while (0)
66#define arch_read_trylock(lock) ({ barrier(); (void)(lock); 1; })
67#define arch_write_trylock(lock) ({ barrier(); (void)(lock); 1; })
68#define arch_read_unlock(lock) do { barrier(); (void)(lock); } while (0)
69#define arch_write_unlock(lock) do { barrier(); (void)(lock); } while (0)
70
71#endif /* __LINUX_SPINLOCK_UP_H */