smp_lock.h





#ifndef __I386_SMPLOCK_H
#define __I386_SMPLOCK_H

#ifdef __SMP__

/*
* Locking the kernel
*/

extern __inline void lock_kernel(void)
{
unsigned long flags;
int proc = smp_processor_id();

save_flags(flags);
cli();
/* set_bit works atomic in SMP machines */
while(set_bit(0, (void *)&kernel_flag))
{
/*
* We just start another level if we have the lock
*/
if (proc == active_kernel_processor)
break;
do
{
#ifdef __SMP_PROF__
smp_spins[smp_processor_id()]++;
#endif
/*
* Doing test_bit here doesn't lock the bus
*/
if (test_bit(proc, (void *)&smp_invalidate_needed))
if (clear_bit(proc, (void *)&smp_invalidate_needed))
local_flush_tlb();
}
while(test_bit(0, (void *)&kernel_flag));
}
/*
* We got the lock, so tell the world we are here and increment
* the level counter
*/
active_kernel_processor = proc;
kernel_counter++;
restore_flags(flags);
}

extern __inline void unlock_kernel(void)
{
unsigned long flags;
save_flags(flags);
cli();
/*
* If it's the last level we have in the kernel, then
* free the lock
*/
if (kernel_counter == 0)
panic("Kernel counter wrong.\n"); /* FIXME: Why is kernel_counter sometimes 0 here? */

if(! --kernel_counter)
{
active_kernel_processor = NO_PROC_ID;
clear_bit(0, (void *)&kernel_flag);
}
restore_flags(flags);
}

#endif
#endif