1 /*
2  * <asm/smplock.h>
3  *
4  * Default SMP lock implementation
5  */
6 #include <linux/sched.h>
7 #include <linux/interrupt.h>
8 #include <linux/spinlock.h>
9 
10 extern spinlock_t kernel_flag;
11 
12 #define kernel_locked()			\
13 	(spin_is_locked(&kernel_flag) &&\
14 	 (current->lock_depth >= 0))
15 
16 /*
17  * Release global kernel lock and global interrupt lock
18  */
19 #define release_kernel_lock(task, cpu) \
20 do { \
21 	if (task->lock_depth >= 0) \
22 		spin_unlock(&kernel_flag); \
23 	release_irqlock(cpu); \
24 	__sti(); \
25 } while (0)
26 
27 /*
28  * Re-acquire the kernel lock
29  */
30 #define reacquire_kernel_lock(task) \
31 do { \
32 	if (task->lock_depth >= 0) \
33 		spin_lock(&kernel_flag); \
34 } while (0)
35 
36 
37 /*
38  * Getting the big kernel lock.
39  *
40  * This cannot happen asynchronously,
41  * so we only need to worry about other
42  * CPU's.
43  */
44 #define lock_kernel() \
45 do { \
46 	if (!++current->lock_depth) \
47 		spin_lock(&kernel_flag); \
48 } while(0)
49 
50 #define unlock_kernel() \
51 do { \
52 	if (--current->lock_depth < 0) \
53 		spin_unlock(&kernel_flag); \
54 } while(0)
55