include/asm-i386/smplock.h

   1 /*
   2  * <asm/smplock.h>
   3  *
   4  * i386 SMP lock implementation
   5  */
   6 #include <linux/interrupt.h>
   7 #include <linux/spinlock.h>
   8 #include <linux/sched.h>
   9 #include <asm/current.h>
  10
  11 extern spinlock_t kernel_flag;
  12
  13 /*
  14  * Release global kernel lock and global interrupt lock
  15  */
  16 #define release_kernel_lock(task, cpu) \
  17 do { \
  18         if (task->lock_depth >= 0) \
  19                 spin_unlock(&kernel_flag); \
  20         release_irqlock(cpu); \
  21         __sti(); \
  22 } while (0)
  23
  24 /*
  25  * Re-acquire the kernel lock
  26  */
  27 #define reacquire_kernel_lock(task) \
  28 do { \
  29         if (task->lock_depth >= 0) \
  30                 spin_lock(&kernel_flag); \
  31 } while (0)
  32
  33
  34 /*
  35  * Getting the big kernel lock.
  36  *
  37  * This cannot happen asynchronously,
  38  * so we only need to worry about other
  39  * CPU's.
  40  */
  41 extern __inline__ void lock_kernel(void)
  42 {
  43 #if 1
  44         if (!++current->lock_depth)
  45                 spin_lock(&kernel_flag);
  46 #else
  47         __asm__ __volatile__(
  48                 "incl %1\n\t"
  49                 "jne 9f"
  50                 spin_lock_string
  51                 "\n9:"
  52                 :"=m" (__dummy_lock(&kernel_flag)),
  53                  "=m" (current->lock_depth));
  54 #endif
  55 }
  56
  57 extern __inline__ void unlock_kernel(void)
  58 {
  59         if (current->lock_depth < 0)
  60                 BUG();
  61 #if 1
  62         if (--current->lock_depth < 0)
  63                 spin_unlock(&kernel_flag);
  64 #else
  65         __asm__ __volatile__(
  66                 "decl %1\n\t"
  67                 "jns 9f\n\t"
  68                 spin_unlock_string
  69                 "\n9:"
  70                 :"=m" (__dummy_lock(&kernel_flag)),
  71                  "=m" (current->lock_depth));
  72 #endif
  73 }