/*
* Acquire a usimple_lock.
*
* MACH_RT: Returns with preemption disabled. Note
* that the hw_lock routines are responsible for
* maintaining preemption state.
*/
void
usimple_lock(
usimple_lock_t l)
{
int i;
unsigned int timeouttb; /* Used to convert time to timebase ticks */
pc_t pc;
#if ETAP_LOCK_TRACE
etap_time_t start_wait_time;
int no_miss_info = 0;
#endif /* ETAP_LOCK_TRACE */
#if USLOCK_DEBUG
int count = 0;
#endif /* USLOCK_DEBUG */
OBTAIN_PC(pc, l);
USLDBG(usld_lock_pre(l, pc));
#if ETAP_LOCK_TRACE
ETAP_TIME_CLEAR(start_wait_time);
#endif /* ETAP_LOCK_TRACE */
while (!hw_lock_try(&l->interlock)) {
ETAPCALL(if (no_miss_info++ == 0)
start_wait_time = etap_simplelock_miss(l));
while (hw_lock_held(&l->interlock)) {
/*
* Spin watching the lock value in cache,
* without consuming external bus cycles.
* On most SMP architectures, the atomic
* instruction(s) used by hw_lock_try
* cost much, much more than an ordinary
* memory read.
*/
#if USLOCK_DEBUG
if (count++ > max_lock_loops
#if MACH_KDB && NCPUS > 1
&& l != &kdb_lock
#endif /* MACH_KDB && NCPUS > 1 */
) {
if (l == &printf_lock) {
return;
}
mp_disable_preemption();
#if MACH_KDB
db_printf("cpu %d looping on simple_lock(%x)"
"(=%x)",
cpu_number(), l,
*hw_lock_addr(l->interlock));
db_printf(" called by %x\n", pc);
#endif
Debugger("simple lock deadlock detection");
count = 0;
mp_enable_preemption();
}
#endif /* USLOCK_DEBUG */
}
}
ETAPCALL(etap_simplelock_hold(l, pc, start_wait_time));
USLDBG(usld_lock_post(l, pc));
}
void
db_print_mutex (
mutex_t * addr)
{
db_printf ("%08x %6d %7d",
addr, *hw_lock_addr(addr->locked), addr->waiters);
#if MACH_LDEBUG
db_printf (" %08x ", addr->thread);
db_printsym (addr->pc, DB_STGY_ANY);
#endif /* MACH_LDEBUG */
db_printf ("\n");
}
void
db_print_simple_lock (
simple_lock_t addr)
{
db_printf ("%08x %3d", addr, *hw_lock_addr(addr->interlock));
#if USLOCK_DEBUG
db_printf (" %08x", addr->debug.lock_thread);
db_printf (" %08x ", addr->debug.duration[1]);
db_printsym ((int)addr->debug.lock_pc, DB_STGY_ANY);
#endif /* USLOCK_DEBUG */
db_printf ("\n");
}
