From: Stephen Hemminger <[EMAIL PROTECTED]>
Date: Thu, 26 Oct 2006 18:04:02 -0700
> On Thu, 26 Oct 2006 17:12:47 -0700 (PDT)
> David Miller <[EMAIL PROTECTED]> wrote:
>
> > From: Stephen Hemminger <[EMAIL PROTECTED]>
> > Date: Thu, 26 Oct 2006 15:46:49 -0700
> >
> > > @@ -188,19 +186,14 @@ void netpoll_poll(struct netpoll *np)
> > > static void refill_skbs(void)
> > > {
> > > struct sk_buff *skb;
> > > - unsigned long flags;
> > >
> > > - spin_lock_irqsave(&skb_list_lock, flags);
> > > - while (nr_skbs < MAX_SKBS) {
> > > + while (skb_queue_len(&skb_pool) < MAX_SKBS) {
> >
> > Previously, the lock actually protected nr_skbs from going over
> > MAX_SKBS properly, but the new code does not. skb_queue_len()
> > is lockless.
> >
> > Stephen, I really appreciate your efforts to clean up netpoll,
> > but on every iteration I am finding simple errors on the first
> > patch every time.
>
> racing over by one is not a big issue.
It's potentially racing by more than that, depending upon whether any
cpus take interrupts and are stalled for significiant time after
making the decision to add. The upper bound is something like
(2 * NCPUS) - 1.
It's a bug Stephen.
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