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
   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 */