LXR linux-bk/include/linux/smp

   1#ifndef __LINUX_SMPLOCK_H
   2#define __LINUX_SMPLOCK_H
   3
   4#include <linux/config.h>
   5#include <linux/sched.h>
   6#include <linux/spinlock.h>
   7
   8#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
   9
  10extern spinlock_t kernel_flag;
  11
  12#define kernel_locked()         (current->lock_depth >= 0)
  13
  14#define get_kernel_lock()       spin_lock(&kernel_flag)
  15#define put_kernel_lock()       spin_unlock(&kernel_flag)
  16
  17/*
  18 * Release global kernel lock.
  19 */
  20static inline void release_kernel_lock(struct task_struct *task)
  21{
  22        if (unlikely(task->lock_depth >= 0))
  23                put_kernel_lock();
  24}
  25
  26/*
  27 * Re-acquire the kernel lock
  28 */
  29static inline void reacquire_kernel_lock(struct task_struct *task)
  30{
  31        if (unlikely(task->lock_depth >= 0))
  32                get_kernel_lock();
  33}
  34
  35/*
  36 * Getting the big kernel lock.
  37 *
  38 * This cannot happen asynchronously,
  39 * so we only need to worry about other
  40 * CPU's.
  41 */
  42static inline void lock_kernel(void)
  43{
  44        int depth = current->lock_depth+1;
  45        if (likely(!depth))
  46                get_kernel_lock();
  47        current->lock_depth = depth;
  48}
  49
  50static inline void unlock_kernel(void)
  51{
  52        BUG_ON(current->lock_depth < 0);
  53        if (likely(--current->lock_depth < 0))
  54                put_kernel_lock();
  55}
  56
  57#else
  58
  59#define lock_kernel()                           do { } while(0)
  60#define unlock_kernel()                         do { } while(0)
  61#define release_kernel_lock(task)               do { } while(0)
  62#define reacquire_kernel_lock(task)             do { } while(0)
  63#define kernel_locked()                         1
  64
  65#endif /* CONFIG_SMP || CONFIG_PREEMPT */
  66#endif /* __LINUX_SMPLOCK_H */
  67