netdev - Re: [PATCH 3/3] ifb: move tq from ifb

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Message-ID: <AANLkTimy_dK0uDCWqo3AZBKSvod+KnE6Om-CxrbFmPj+@mail.gmail.com>
Date:	Sat, 4 Dec 2010 22:45:19 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	hadi@...erus.ca
Cc:	Jarek Poplawski <jarkao2@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH 3/3] ifb: move tq from ifb_private

On Sat, Dec 4, 2010 at 10:28 PM, jamal <hadi@...erus.ca> wrote:
> On Sat, 2010-12-04 at 14:15 +0100, Jarek Poplawski wrote:
>
>> > @@ -87,7 +83,7 @@ static void ri_tasklet(unsigned long dev)
>> >                     rcu_read_unlock();
>> >                     dev_kfree_skb(skb);
>> >                     stats->tx_dropped++;
>> > -                   break;
>> > +                   continue;
>>
>> IMHO this line is a bugfix and should be a separate patch (for stable).
>
> Should be separate, yes.
> Bug? no.

If we breaks the loop when there are still skbs in tq and no skb in
rq, the skbs will be left in txq until new skbs are enqueued into rq.
In rare cases, no new skb is queued, then these skbs will stay in rq
forever.

-       if (__netif_tx_trylock(txq)) {
-               if ((skb = skb_peek(&dp->rq)) == NULL) {
-                       dp->tasklet_pending = 0;
-                       if (netif_queue_stopped(_dev))
-                               netif_wake_queue(_dev);
-               } else {
-                       __netif_tx_unlock(txq);
-                       goto resched;
-               }
-               __netif_tx_unlock(txq);
-       } else {
-resched:
-               dp->tasklet_pending = 1;
-               tasklet_schedule(&dp->ifb_tasklet);
-       }
-


-- 
Regards,
Changli Gao(xiaosuo@...il.com)
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