include/asm-cris/smp_lock.h

   1 #ifndef __CRIS_SMPLOCK_H
   2 #define __CRIS_SMPLOCK_H
   3
   4 #include <linux/config.h>
   5
   6 #ifdef CONFIG_SMP
   7
   8 #error "SMP is not supported for CRIS"
   9
  10 /*
  11  *      Locking the kernel
  12  */
  13
  14 extern __inline void lock_kernel(void)
  15 {
  16         unsigned long flags;
  17         int proc = smp_processor_id();
  18
  19         save_flags(flags);
  20         cli();
  21         /* set_bit works atomic in SMP machines */
  22         while(set_bit(0, (void *)&kernel_flag))
  23         {
  24                 /*
  25                  *      We just start another level if we have the lock
  26                  */
  27                 if (proc == active_kernel_processor)
  28                         break;
  29                 do
  30                 {
  31 #ifdef __SMP_PROF__
  32                         smp_spins[smp_processor_id()]++;
  33 #endif
  34                         /*
  35                          *      Doing test_bit here doesn't lock the bus
  36                          */
  37                         if (test_bit(proc, (void *)&smp_invalidate_needed))
  38                                 if (clear_bit(proc, (void *)&smp_invalidate_needed))
  39                                         local_flush_tlb();
  40                 }
  41                 while(test_bit(0, (void *)&kernel_flag));
  42         }
  43         /*
  44          *      We got the lock, so tell the world we are here and increment
  45          *      the level counter
  46          */
  47         active_kernel_processor = proc;
  48         kernel_counter++;
  49         restore_flags(flags);
  50 }
  51
  52 extern __inline void unlock_kernel(void)
  53 {
  54         unsigned long flags;
  55         save_flags(flags);
  56         cli();
  57         /*
  58          *      If it's the last level we have in the kernel, then
  59          *      free the lock
  60          */
  61         if (kernel_counter == 0)
  62                 panic("Kernel counter wrong.\n"); /* FIXME: Why is kernel_counter sometimes 0 here? */
  63
  64         if(! --kernel_counter)
  65         {
  66                 active_kernel_processor = NO_PROC_ID;
  67                 clear_bit(0, (void *)&kernel_flag);
  68         }
  69         restore_flags(flags);
  70 }
  71
  72 #endif
  73 #endif