/include/linux/smp_lock.h

 1#ifndef __LINUX_SMPLOCK_H
 2#define __LINUX_SMPLOCK_H
 3
 4#ifdef CONFIG_LOCK_KERNEL
 5#include <linux/sched.h>
 6
 7#define kernel_locked()		(current->lock_depth >= 0)
 8
 9extern int __lockfunc __reacquire_kernel_lock(void);
10extern void __lockfunc __release_kernel_lock(void);
11
12/*
13 * Release/re-acquire global kernel lock for the scheduler
14 */
15#define release_kernel_lock(tsk) do { 		\
16	if (unlikely((tsk)->lock_depth >= 0))	\
17		__release_kernel_lock();	\
18} while (0)
19
20static inline int reacquire_kernel_lock(struct task_struct *task)
21{
22	if (unlikely(task->lock_depth >= 0))
23		return __reacquire_kernel_lock();
24	return 0;
25}
26
27extern void __lockfunc
28_lock_kernel(const char *func, const char *file, int line)
29__acquires(kernel_lock);
30
31extern void __lockfunc
32_unlock_kernel(const char *func, const char *file, int line)
33__releases(kernel_lock);
34
35#define lock_kernel() do {					\
36	_lock_kernel(__func__, __FILE__, __LINE__);		\
37} while (0)
38
39#define unlock_kernel()	do {					\
40	_unlock_kernel(__func__, __FILE__, __LINE__);		\
41} while (0)
42
43/*
44 * Various legacy drivers don't really need the BKL in a specific
45 * function, but they *do* need to know that the BKL became available.
46 * This function just avoids wrapping a bunch of lock/unlock pairs
47 * around code which doesn't really need it.
48 */
49static inline void cycle_kernel_lock(void)
50{
51	lock_kernel();
52	unlock_kernel();
53}
54
55#else
56
57#define lock_kernel()
58#define unlock_kernel()
59#define release_kernel_lock(task)		do { } while(0)
60#define cycle_kernel_lock()			do { } while(0)
61#define reacquire_kernel_lock(task)		0
62#define kernel_locked()				1
63
64#endif /* CONFIG_LOCK_KERNEL */
65#endif /* __LINUX_SMPLOCK_H */