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
  28 _lock_kernel(const char *func, const char *file, int line)
  29 __acquires(kernel_lock);
  30
  31 extern void __lockfunc
  32 _unlock_kernel(const char *func, const char *file, int line)
  33 __releases(kernel_lock);
  34
  35 #define lock_kernel() do {                                      \
  36         _lock_kernel(__func__, __FILE__, __LINE__);             \
  37 } while (0)
  38
  39 #define unlock_kernel() do {                                    \
  40         _unlock_kernel(__func__, __FILE__, __LINE__);           \
  41 } while (0)
  42
  43 /*
  44  * Various legacy drivers don't really need the BKL in a specific
  45  * function, but they *do* need to know that the BKL became available.
  46  * This function just avoids wrapping a bunch of lock/unlock pairs
  47  * around code which doesn't really need it.
  48  */
  49 static inline void cycle_kernel_lock(void)
  50 {
  51         lock_kernel();
  52         unlock_kernel();
  53 }
  54
  55 #else
  56
  57 #ifdef CONFIG_BKL /* provoke build bug if not set */
  58 #define lock_kernel()
  59 #define unlock_kernel()
  60 #define cycle_kernel_lock()                     do { } while(0)
  61 #define kernel_locked()                         1
  62 #endif /* CONFIG_BKL */
  63
  64 #define release_kernel_lock(task)               do { } while(0)
  65 #define reacquire_kernel_lock(task)             0
  66
  67 #endif /* CONFIG_LOCK_KERNEL */
  68 #endif /* __LINUX_SMPLOCK_H */