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