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/* $Id: debuglocks.c,v 1.11 2001/09/20 00:35:31 davem Exp $
* debuglocks.c: Debugging versions of SMP locking primitives.
*
* Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
* Copyright (C) 1998-99 Anton Blanchard (anton@progsoc.uts.edu.au)
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/threads.h> /* For NR_CPUS */
#include <linux/spinlock.h>
#include <asm/psr.h>
#include <asm/system.h>
/* To enable this code, just define SPIN_LOCK_DEBUG in asm/spinlock.h */
#ifdef SPIN_LOCK_DEBUG
/* Some notes on how these debugging routines work. When a lock is acquired
* an extra debugging member lock->owner_pc is set to the caller of the lock
* acquisition routine. Right before releasing a lock, the debugging program
* counter is cleared to zero.
*
* Furthermore, since PC's are 4 byte aligned on Sparc, we stuff the CPU
* number of the owner in the lowest two bits.
*/
#define STORE_CALLER(A) __asm__ __volatile__("mov %%i7, %0" : "=r" (A));
static inline void show(char *str, spinlock_t *lock, unsigned long caller)
{
int cpu = smp_processor_id();
printk("%s(%p) CPU#%d stuck at %08lx, owner PC(%08lx):CPU(%lx)\n",str,
lock, cpu, caller, lock->owner_pc & ~3, lock->owner_pc & 3);
}
static inline void show_read(char *str, rwlock_t *lock, unsigned long caller)
{
int cpu = smp_processor_id();
printk("%s(%p) CPU#%d stuck at %08lx, owner PC(%08lx):CPU(%lx)\n", str,
lock, cpu, caller, lock->owner_pc & ~3, lock->owner_pc & 3);
}
static inline void show_write(char *str, rwlock_t *lock, unsigned long caller)
{
int cpu = smp_processor_id();
int i;
printk("%s(%p) CPU#%d stuck at %08lx, owner PC(%08lx):CPU(%lx)", str,
lock, cpu, caller, lock->owner_pc & ~3, lock->owner_pc & 3);
for(i = 0; i < NR_CPUS; i++)
printk(" reader[%d]=%08lx", i, lock->reader_pc[i]);
printk("\n");
}
#undef INIT_STUCK
#define INIT_STUCK 100000000
void _do_spin_lock(spinlock_t *lock, char *str)
{
unsigned long caller;
unsigned long val;
int cpu = smp_processor_id();
int stuck = INIT_STUCK;
STORE_CALLER(caller);
again:
__asm__ __volatile__("ldstub [%1], %0" : "=r" (val) : "r" (&(lock->lock)));
if(val) {
while(lock->lock) {
if (!--stuck) {
show(str, lock, caller);
stuck = INIT_STUCK;
}
barrier();
}
goto again;
}
lock->owner_pc = (cpu & 3) | (caller & ~3);
}
int _spin_trylock(spinlock_t *lock)
{
unsigned long val;
unsigned long caller;
int cpu = smp_processor_id();
STORE_CALLER(caller);
__asm__ __volatile__("ldstub [%1], %0" : "=r" (val) : "r" (&(lock->lock)));
if(!val) {
/* We got it, record our identity for debugging. */
lock->owner_pc = (cpu & 3) | (caller & ~3);
}
return val == 0;
}
void _do_spin_unlock(spinlock_t *lock)
{
lock->owner_pc = 0;
barrier();
lock->lock = 0;
}
void _do_read_lock(rwlock_t *rw, char *str)
{
unsigned long caller;
unsigned long val;
int cpu = smp_processor_id();
int stuck = INIT_STUCK;
STORE_CALLER(caller);
wlock_again:
__asm__ __volatile__("ldstub [%1 + 3], %0" : "=r" (val) : "r" (&(rw->lock)));
if(val) {
while(rw->lock & 0xff) {
if (!--stuck) {
show_read(str, rw, caller);
stuck = INIT_STUCK;
}
barrier();
}
goto wlock_again;
}
rw->reader_pc[cpu] = caller;
barrier();
rw->lock++;
}
void _do_read_unlock(rwlock_t *rw, char *str)
{
unsigned long caller;
unsigned long val;
int cpu = smp_processor_id();
int stuck = INIT_STUCK;
STORE_CALLER(caller);
wlock_again:
__asm__ __volatile__("ldstub [%1 + 3], %0" : "=r" (val) : "r" (&(rw->lock)));
if(val) {
while(rw->lock & 0xff) {
if (!--stuck) {
show_read(str, rw, caller);
stuck = INIT_STUCK;
}
barrier();
}
goto wlock_again;
}
rw->reader_pc[cpu] = 0;
barrier();
rw->lock -= 0x1ff;
}
void _do_write_lock(rwlock_t *rw, char *str)
{
unsigned long caller;
unsigned long val;
int cpu = smp_processor_id();
int stuck = INIT_STUCK;
STORE_CALLER(caller);
wlock_again:
__asm__ __volatile__("ldstub [%1 + 3], %0" : "=r" (val) : "r" (&(rw->lock)));
if(val) {
wlock_wait:
while(rw->lock) {
if (!--stuck) {
show_write(str, rw, caller);
stuck = INIT_STUCK;
}
barrier();
}
goto wlock_again;
}
if (rw->lock & ~0xff) {
*(((unsigned char *)&rw->lock)+3) = 0;
barrier();
goto wlock_wait;
}
barrier();
rw->owner_pc = (cpu & 3) | (caller & ~3);
}
void _do_write_unlock(rwlock_t *rw)
{
rw->owner_pc = 0;
barrier();
rw->lock = 0;
}
#endif /* SPIN_LOCK_DEBUG */
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