On Thu Jan 2 17:32:08 EST 2014, [email protected] wrote:
> On Thu Jan 2 16:55:59 EST 2014, [email protected] wrote:
> > i was investigating all callers of postnote() for bugs that could
> > lead to spurious notes like the alarm race i described before. btw
> > this has been fixed too. the key is to recheck p->alarm while holding
> > p->debug qlock. once you have it, the process cannot exit under you.
>
> cool. if that's the protocol, doesn't the debug lock need to be held whenever
> up->alarm is modified?
checkalarms will hang during rollover. suppose sys->ticks = 1<<31,
then (long)((1<<31) - 0) = -2147483648. this will stay negative for a
2147483648/HZ seconds.
i think this is necessary:
void
checkalarms(void)
{
Proc *p;
ulong now;
p = alarms.head;
now = sys->ticks;
if(p != nil)
if(p->alarm == 0 || (long)(now - p->alarm) >= 0)
wakeup(&alarmr);
}
- erik
