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C/C++ Source or Header  |  2008-12-24  |  1.4 KB  |  53 lines
  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.  
  9. extern int __lockfunc __reacquire_kernel_lock(void);
  10. extern 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.  
  20. static 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.  
  27. extern void __lockfunc lock_kernel(void)    __acquires(kernel_lock);
  28. extern void __lockfunc unlock_kernel(void)    __releases(kernel_lock);
  29.  
  30. /*
  31.  * Various legacy drivers don't really need the BKL in a specific
  32.  * function, but they *do* need to know that the BKL became available.
  33.  * This function just avoids wrapping a bunch of lock/unlock pairs
  34.  * around code which doesn't really need it.
  35.  */
  36. static inline void cycle_kernel_lock(void)
  37. {
  38.     lock_kernel();
  39.     unlock_kernel();
  40. }
  41.  
  42. #else
  43.  
  44. #define lock_kernel()                do { } while(0)
  45. #define unlock_kernel()                do { } while(0)
  46. #define release_kernel_lock(task)        do { } while(0)
  47. #define cycle_kernel_lock()            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 */
  53.