include/asm-arm/smplock.h

   1 /*
   2  * <asm/smplock.h>
   3  *
   4  * Default SMP lock implementation
   5  */
   6 #include <linux/config.h>
   7 #include <linux/interrupt.h>
   8 #include <linux/spinlock.h>
   9
  10 extern spinlock_t kernel_flag;
  11
  12 #ifdef CONFIG_PREEMPT
  13 #define kernel_locked()         preempt_get_count()
  14 #else
  15 #define kernel_locked()         spin_is_locked(&kernel_flag)
  16 #endif
  17
  18 /*
  19  * Release global kernel lock and global interrupt lock
  20  */
  21 #define release_kernel_lock(task, cpu)          \
  22 do {                                            \
  23         if (unlikely(task->lock_depth >= 0))    \
  24                 spin_unlock(&kernel_flag);      \
  25 } while (0)
  26
  27 /*
  28  * Re-acquire the kernel lock
  29  */
  30 #define reacquire_kernel_lock(task)             \
  31 do {                                            \
  32         if (unlikely(task->lock_depth >= 0))    \
  33                 spin_lock(&kernel_flag);        \
  34 } while (0)
  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 #ifdef CONFIG_PREEMPT
  47         if (current->lock_depth == -1)
  48                 spin_lock(&kernel_flag);
  49         ++current->lock_depth;
  50 #else
  51         if (!++current->lock_depth)
  52                 spin_lock(&kernel_flag);
  53 #endif
  54 }
  55
  56 static inline void unlock_kernel(void)
  57 {
  58         if (--current->lock_depth < 0)
  59                 spin_unlock(&kernel_flag);
  60 }