LXR linux/include/linux/smp

   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
   9extern int __lockfunc __reacquire_kernel_lock(void);
  10extern 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
  20static 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
  27extern void __lockfunc lock_kernel(void)        __acquires(kernel_lock);
  28extern 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 */
  36static 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