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 #define kernel_locked()         spin_is_locked(&kernel_flag)
  14
  15 /*
  16  * Release global kernel lock and global interrupt lock
  17  */
  18 #define release_kernel_lock(task, cpu) \
  19 do { \
  20         if (task->lock_depth >= 0) \
  21                 spin_unlock(&kernel_flag); \
  22         release_irqlock(cpu); \
  23         __sti(); \
  24 } while (0)
  25
  26 /*
  27  * Re-acquire the kernel lock
  28  */
  29 #define reacquire_kernel_lock(task) \
  30 do { \
  31         if (task->lock_depth >= 0) \
  32                 spin_lock(&kernel_flag); \
  33 } while (0)
  34
  35
  36 /*
  37  * Getting the big kernel lock.
  38  *
  39  * This cannot happen asynchronously,
  40  * so we only need to worry about other
  41  * CPU's.
  42  */
  43 extern __inline__ void lock_kernel(void)
  44 {
  45 #if 1
  46         if (!++current->lock_depth)
  47                 spin_lock(&kernel_flag);
  48 #else
  49         __asm__ __volatile__(
  50                 "incl %1\n\t"
  51                 "jne 9f"
  52                 spin_lock_string
  53                 "\n9:"
  54                 :"=m" (__dummy_lock(&kernel_flag)),
  55                  "=m" (current->lock_depth));
  56 #endif
  57 }
  58
  59 extern __inline__ void unlock_kernel(void)
  60 {
  61         if (current->lock_depth < 0)
  62                 BUG();
  63 #if 1
  64         if (--current->lock_depth < 0)
  65                 spin_unlock(&kernel_flag);
  66 #else
  67         __asm__ __volatile__(
  68                 "decl %1\n\t"
  69                 "jns 9f\n\t"
  70                 spin_unlock_string
  71                 "\n9:"
  72                 :"=m" (__dummy_lock(&kernel_flag)),
  73                  "=m" (current->lock_depth));
  74 #endif
  75 }