/* Block the currently-executing domain until a pertinent event occurs. */
static long do_block(void)
{
struct vcpu *v = current;
local_event_delivery_enable();
set_bit(_VPF_blocked, &v->pause_flags);
/* Check for events /after/ blocking: avoids wakeup waiting race. */
if ( local_events_need_delivery() )
{
clear_bit(_VPF_blocked, &v->pause_flags);
}
else
{
TRACE_2D(TRC_SCHED_BLOCK, v->domain->domain_id, v->vcpu_id);
raise_softirq(SCHEDULE_SOFTIRQ);
}
return 0;
}
static long do_poll(struct sched_poll *sched_poll)
{
struct vcpu *v = current;
struct domain *d = v->domain;
evtchn_port_t port;
long rc;
unsigned int i;
/* Fairly arbitrary limit. */
if ( sched_poll->nr_ports > 128 )
return -EINVAL;
if ( !guest_handle_okay(sched_poll->ports, sched_poll->nr_ports) )
return -EFAULT;
set_bit(_VPF_blocked, &v->pause_flags);
v->poll_evtchn = -1;
set_bit(v->vcpu_id, d->poll_mask);
#ifndef CONFIG_X86 /* set_bit() implies mb() on x86 */
/* Check for events /after/ setting flags: avoids wakeup waiting race. */
smp_mb();
/*
* Someone may have seen we are blocked but not that we are polling, or
* vice versa. We are certainly being woken, so clean up and bail. Beyond
* this point others can be guaranteed to clean up for us if they wake us.
*/
rc = 0;
if ( (v->poll_evtchn == 0) ||
!test_bit(_VPF_blocked, &v->pause_flags) ||
!test_bit(v->vcpu_id, d->poll_mask) )
goto out;
#endif
rc = 0;
if ( local_events_need_delivery() )
goto out;
for ( i = 0; i < sched_poll->nr_ports; i++ )
{
rc = -EFAULT;
if ( __copy_from_guest_offset(&port, sched_poll->ports, i, 1) )
goto out;
rc = -EINVAL;
if ( port >= MAX_EVTCHNS(d) )
goto out;
rc = 0;
if ( test_bit(port, &shared_info(d, evtchn_pending)) )
goto out;
}
if ( sched_poll->nr_ports == 1 )
v->poll_evtchn = port;
if ( sched_poll->timeout != 0 )
set_timer(&v->poll_timer, sched_poll->timeout);
TRACE_2D(TRC_SCHED_BLOCK, d->domain_id, v->vcpu_id);
raise_softirq(SCHEDULE_SOFTIRQ);
return 0;
out:
v->poll_evtchn = 0;
clear_bit(v->vcpu_id, d->poll_mask);
clear_bit(_VPF_blocked, &v->pause_flags);
return rc;
}
