On 06/25, Oleg Nesterov wrote:
>
> On 06/25, Paul E. McKenney wrote:
> >
> > On Mon, Jun 25, 2007 at 02:43:32PM +0400, Oleg Nesterov wrote:
> > >
> > > Sadly, you can't use srcu/qrcu because it doesn't handle timeouts.
> >
> > Interesting... So the thought is to have a synchronize_srcu_timeout()
> > or something similar that waited for a grace period to elapse or for
> > a timeout to expire, whichever comes first? It should not be too hard
> > to arrange something, if needed.
>
> Yes. As for qrcu (see http://marc.info/?t=116484476500001), I think it is
> easy.
> First, we add "int interrupted" into struct qrcu_struct, then something like
> this
Even simpler, we don't need ->interrupted.
long synchronize_qrcu_timeout(struct qrcu_struct *qp, long tout)
{
int idx, prv;
smp_mb();
mutex_lock(&qp->mutex);
idx = qp->completed & 0x1;
prv = idx ^ 0x1;
if (unlikely(atomic_read(qp->ctr + prv))) {
// the previous call has not succeed,
// finish the wait
__wait_event_timeout(qp->wq, !atomic_read(qp->ctr +
prv), tout);
if (unlikely(!tout))
goto out;
}
if (atomic_read(qp->ctr + idx) == 1)
goto out;
atomic_inc(qp->ctr + prv);
qp->completed++;
atomic_dec(qp->ctr + idx);
__wait_event_timeout(qp->wq, !atomic_read(qp->ctr + idx), tout);
out:
mutex_unlock(&qp->mutex);
smp_mb();
return tout;
}
Oleg.
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