Merge branch 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik...
[linux-2.6] / 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 #include <linux/spinlock.h>
7
8 #define kernel_locked()         (current->lock_depth >= 0)
9
10 extern int __lockfunc __reacquire_kernel_lock(void);
11 extern void __lockfunc __release_kernel_lock(void);
12
13 /*
14  * Release/re-acquire global kernel lock for the scheduler
15  */
16 #define release_kernel_lock(tsk) do {           \
17         if (unlikely((tsk)->lock_depth >= 0))   \
18                 __release_kernel_lock();        \
19 } while (0)
20
21 /*
22  * Non-SMP kernels will never block on the kernel lock,
23  * so we are better off returning a constant zero from
24  * reacquire_kernel_lock() so that the compiler can see
25  * it at compile-time.
26  */
27 #if defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT_BKL)
28 # define return_value_on_smp return
29 #else
30 # define return_value_on_smp
31 #endif
32
33 static inline int reacquire_kernel_lock(struct task_struct *task)
34 {
35         if (unlikely(task->lock_depth >= 0))
36                 return_value_on_smp __reacquire_kernel_lock();
37         return 0;
38 }
39
40 extern void __lockfunc lock_kernel(void)        __acquires(kernel_lock);
41 extern void __lockfunc unlock_kernel(void)      __releases(kernel_lock);
42
43 #else
44
45 #define lock_kernel()                           do { } while(0)
46 #define unlock_kernel()                         do { } while(0)
47 #define release_kernel_lock(task)               do { } while(0)
48 #define reacquire_kernel_lock(task)             0
49 #define kernel_locked()                         1
50
51 #endif /* CONFIG_LOCK_KERNEL */
52 #endif /* __LINUX_SMPLOCK_H */