LXR linux/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#ifdef CONFIG_LOCK_KERNEL
   9
  10#define kernel_locked()         (current->lock_depth >= 0)
  11
  12extern int __lockfunc __reacquire_kernel_lock(void);
  13extern void __lockfunc __release_kernel_lock(void);
  14
  15/*
  16 * Release/re-acquire global kernel lock for the scheduler
  17 */
  18#define release_kernel_lock(tsk) do {           \
  19        if (unlikely((tsk)->lock_depth >= 0))   \
  20                __release_kernel_lock();        \
  21} while (0)
  22
  23/*
  24 * Non-SMP kernels will never block on the kernel lock,
  25 * so we are better off returning a constant zero from
  26 * reacquire_kernel_lock() so that the compiler can see
  27 * it at compile-time.
  28 */
  29#if defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT_BKL)
  30# define return_value_on_smp return
  31#else
  32# define return_value_on_smp
  33#endif
  34
  35static inline int reacquire_kernel_lock(struct task_struct *task)
  36{
  37        if (unlikely(task->lock_depth >= 0))
  38                return_value_on_smp __reacquire_kernel_lock();
  39        return 0;
  40}
  41
  42extern void __lockfunc lock_kernel(void)        __acquires(kernel_lock);
  43extern void __lockfunc unlock_kernel(void)      __releases(kernel_lock);
  44
  45#else
  46
  47#define lock_kernel()                           do { } while(0)
  48#define unlock_kernel()                         do { } while(0)
  49#define release_kernel_lock(task)               do { } while(0)
  50#define reacquire_kernel_lock(task)             0
  51#define kernel_locked()                         1
  52
  53#endif /* CONFIG_LOCK_KERNEL */
  54#endif /* __LINUX_SMPLOCK_H */
  55