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 extern int __lockfunc __reacquire_kernel_lock(void);
   8 extern void __lockfunc __release_kernel_lock(void);
   9
  10 /*
  11  * Release/re-acquire global kernel lock for the scheduler
  12  */
  13 #define release_kernel_lock(tsk) do {           \
  14         if (unlikely((tsk)->lock_depth >= 0))   \
  15                 __release_kernel_lock();        \
  16 } while (0)
  17
  18 static inline int reacquire_kernel_lock(struct task_struct *task)
  19 {
  20         if (unlikely(task->lock_depth >= 0))
  21                 return __reacquire_kernel_lock();
  22         return 0;
  23 }
  24
  25 extern void __lockfunc
  26 _lock_kernel(const char *func, const char *file, int line)
  27 __acquires(kernel_lock);
  28
  29 extern void __lockfunc
  30 _unlock_kernel(const char *func, const char *file, int line)
  31 __releases(kernel_lock);
  32
  33 #define lock_kernel() do {                                      \
  34         _lock_kernel(__func__, __FILE__, __LINE__);             \
  35 } while (0)
  36
  37 #define unlock_kernel() do {                                    \
  38         _unlock_kernel(__func__, __FILE__, __LINE__);           \
  39 } while (0)
  40
  41 /*
  42  * Various legacy drivers don't really need the BKL in a specific
  43  * function, but they *do* need to know that the BKL became available.
  44  * This function just avoids wrapping a bunch of lock/unlock pairs
  45  * around code which doesn't really need it.
  46  */
  47 static inline void cycle_kernel_lock(void)
  48 {
  49         lock_kernel();
  50         unlock_kernel();
  51 }
  52
  53 #else
  54
  55 #ifdef CONFIG_BKL /* provoke build bug if not set */
  56 #define lock_kernel()
  57 #define unlock_kernel()
  58 #define cycle_kernel_lock()                     do { } while(0)
  59 #endif /* CONFIG_BKL */
  60
  61 #define release_kernel_lock(task)               do { } while(0)
  62 #define reacquire_kernel_lock(task)             0
  63
  64 #endif /* CONFIG_LOCK_KERNEL */
  65 #endif /* __LINUX_SMPLOCK_H */