void
__mp_lock(struct __mp_lock *mpl)
{
register_t sr;
struct cpu_info *ci = curcpu();
/*
* Please notice that mpl_count gets incremented twice for the
* first lock. This is on purpose. The way we release the lock
* in mp_unlock is to decrement the mpl_count and then check if
* the lock should be released. Since mpl_count is what we're
* spinning on, decrementing it in mpl_unlock to 0 means that
* we can't clear mpl_cpu, because we're no longer holding the
* lock. In theory mpl_cpu doesn't need to be cleared, but it's
* safer to clear it and besides, setting mpl_count to 2 on the
* first lock makes most of this code much simpler.
*/
while (1) {
sr = disableintr();
if (__cpu_cas(&mpl->mpl_count, 0, 1) == 0) {
mips_sync();
mpl->mpl_cpu = ci;
}
if (mpl->mpl_cpu == ci) {
mpl->mpl_count++;
setsr(sr);
break;
}
setsr(sr);
__mp_lock_spin(mpl);
}
}
void
__mp_lock(struct __mp_lock *mpl)
{
struct __mp_lock_cpu *cpu = &mpl->mpl_cpus[cpu_number()];
u_int64_t s;
s = intr_disable();
if (cpu->mplc_depth++ == 0)
cpu->mplc_ticket = atomic_inc_int_nv(&mpl->mpl_users);
intr_restore(s);
__mp_lock_spin(mpl, cpu->mplc_ticket);
sparc_membar(LoadLoad | LoadStore);
}
void
__mp_lock(struct __mp_lock *mpl)
{
struct cpu_info *ci = curcpu();
uint32_t psr;
uint gcsr;
/*
* Please notice that mpl_count gets incremented twice for the
* first lock. This is on purpose. The way we release the lock
* in mp_unlock is to decrement the mpl_count and then check if
* the lock should be released. Since mpl_count is what we're
* spinning on, decrementing it in mpl_unlock to 0 means that
* we can't clear mpl_cpu, because we're no longer holding the
* lock. In theory mpl_cpu doesn't need to be cleared, but it's
* safer to clear it and besides, setting mpl_count to 2 on the
* first lock makes most of this code much simpler.
*/
for (;;) {
psr = (*ci->ci_mp_atomic_begin)(&mpl->mpl_lock, &gcsr);
if (mpl->mpl_count == 0) {
mpl->mpl_count = 1;
mpl->mpl_cpu = ci;
}
if (mpl->mpl_cpu == ci) {
mpl->mpl_count++;
(*ci->ci_mp_atomic_end)(psr, &mpl->mpl_lock, gcsr);
break;
}
(*ci->ci_mp_atomic_end)(psr, &mpl->mpl_lock, gcsr);
__mp_lock_spin(mpl);
}
}
