include/asm-i386/smplock.h

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