include/asm-i386/smplock.h

   1 #ifndef __ASM_SMPLOCK_H
   2 #define __ASM_SMPLOCK_H
   3
   4 /*
   5  * <asm/smplock.h>
   6  *
   7  * i386 SMP lock implementation
   8  */
   9 #include <linux/interrupt.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/sched.h>
  12 #include <asm/current.h>
  13
  14 extern spinlock_cacheline_t kernel_flag_cacheline;
  15 #define kernel_flag kernel_flag_cacheline.lock
  16
  17 #define kernel_locked()         spin_is_locked(&kernel_flag)
  18
  19 /*
  20  * Release global kernel lock and global interrupt lock
  21  */
  22 #define release_kernel_lock(task, cpu) \
  23 do { \
  24         if (task->lock_depth >= 0) \
  25                 spin_unlock(&kernel_flag); \
  26         release_irqlock(cpu); \
  27         __sti(); \
  28 } while (0)
  29
  30 /*
  31  * Re-acquire the kernel lock
  32  */
  33 #define reacquire_kernel_lock(task) \
  34 do { \
  35         if (task->lock_depth >= 0) \
  36                 spin_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 static __inline__ void lock_kernel(void)
  48 {
  49 #if 1
  50         if (!++current->lock_depth)
  51                 spin_lock(&kernel_flag);
  52 #else
  53         __asm__ __volatile__(
  54                 "incl %1\n\t"
  55                 "jne 9f"
  56                 spin_lock_string
  57                 "\n9:"
  58                 :"=m" (__dummy_lock(&kernel_flag)),
  59                  "=m" (current->lock_depth));
  60 #endif
  61 }
  62
  63 static __inline__ void unlock_kernel(void)
  64 {
  65         if (current->lock_depth < 0)
  66                 out_of_line_bug();
  67 #if 1
  68         if (--current->lock_depth < 0)
  69                 spin_unlock(&kernel_flag);
  70 #else
  71         __asm__ __volatile__(
  72                 "decl %1\n\t"
  73                 "jns 9f\n\t"
  74                 spin_unlock_string
  75                 "\n9:"
  76                 :"=m" (__dummy_lock(&kernel_flag)),
  77                  "=m" (current->lock_depth));
  78 #endif
  79 }
  80
  81 #endif /* __ASM_SMPLOCK_H */