// Only run this on the rust stack
MUST_CHECK bool rust_task::yield() {
bool killed = false;
if (disallow_yield > 0) {
call_on_c_stack(this, (void *)rust_task_yield_fail);
}
// This check is largely superfluous; it's the one after the context swap
// that really matters. This one allows us to assert a useful invariant.
// NB: This takes lifecycle_lock three times, and I believe that none of
// them are actually necessary, as per #3213. Removing the locks here may
// cause *harmless* races with a killer... but I didn't observe any
// substantial performance improvement from removing them, even with
// msgsend-ring-pipes, and also it's my last day, so I'm not about to
// remove them. -- bblum
if (must_fail_from_being_killed()) {
{
scoped_lock with(lifecycle_lock);
assert(!(state == task_state_blocked));
}
killed = true;
}
// Return to the scheduler.
ctx.next->swap(ctx);
if (must_fail_from_being_killed()) {
killed = true;
}
return killed;
}
/*
Called by landing pads during unwinding to figure out which stack segment we
are currently running on and record the stack limit (which was not restored
when unwinding through __morestack).
*/
void
rust_task::reset_stack_limit() {
uintptr_t sp = get_sp();
// Have to do the rest on the C stack because it involves
// freeing stack segments, logging, etc.
// FIXME: This probably doesn't need to happen on the C
// stack now
reset_args ra = {this, sp};
call_on_c_stack(&ra, (void*)reset_stack_limit_on_c_stack);
}