root/include/asm-sparc/smp_lock.h

/* */

INCLUDED FROM

DEFINITIONS

1. lock_kernel
2. unlock_kernel

   1 /* smp_lock.h: Locking and unlocking the kernel on the Sparc.
   2  *
   3  * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
   4  */
   5 
   6 #ifndef __SPARC_SMPLOCK_H
   7 #define __SPARC_SMPLOCK_H
   8 
   9 #include <asm/smp.h>
  10 #include <asm/bitops.h>
  11 #include <asm/atops.h>
  12 #include <asm/pgtable.h>
  13 
  14 #ifdef __SMP__
  15 
  16 /*
  17  *      Locking the kernel 
  18  */
  19 
  20 /* Knock knock... */
  21 extern __inline void lock_kernel(void)
     /*  */
  22 {
  23         unsigned long flags;
  24         int proc = smp_processor_id();
  25 
  26         save_flags(flags); cli(); /* need this on sparc? */
  27         while(ldstub(&kernel_flag)) {
  28                 if(proc == active_kernel_processor)
  29                         break;
  30                 do {
  31 #ifdef __SMP_PROF__             
  32                         smp_spins[smp_processor_id()]++;
  33 #endif                  
  34                         barrier();
  35                 } while(kernel_flag); /* Don't lock the bus more than we have to. */
  36         }
  37         active_kernel_processor = proc;
  38         kernel_counter++;
  39         restore_flags(flags);
  40 }
  41 
  42 /* I want out... */
  43 extern __inline void unlock_kernel(void)
     /*  */
  44 {
  45         unsigned long flags;
  46 
  47         save_flags(flags); cli(); /* need this on sparc? */
  48         if(kernel_counter == 0)
  49                 panic("Bogus kernel counter.\n");
  50 
  51         if(!--kernel_counter) {
  52                 active_kernel_processor = NO_PROC_ID;
  53                 kernel_flag = KLOCK_CLEAR;
  54         }
  55         restore_flags(flags);
  56 }
  57 
  58 #endif /* !(__SPARC_SMPLOCK_H) */
  59 
  60 #endif /* (__SMP__) */

/* */