include/linux/smp_lock.h

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