On 12/18/2017 06:20 PM, Cong Wang wrote:
> On Mon, Dec 18, 2017 at 5:25 PM, John Fastabend
> <john.fastab...@gmail.com> wrote:
>> On 12/18/2017 02:34 PM, Cong Wang wrote:
>>> First, the check of &q->ring.queue against NULL is wrong, it
>>> is always false. We should check the value rather than the address.
>>>
>>
>> Thanks.
>>
>>> Secondly, we need the same check in pfifo_fast_reset() too,
>>> as both ->reset() and ->destroy() are called in qdisc_destroy().
>>>
>>
>> not that it hurts to have the check here, but if init fails
>> in qdisc_create it seems only ->destroy() is called without
>> a ->reset().
>>
>> Is there another path for init() to fail that I'm missing.
>
> Pretty sure ->reset() is called in qdisc_destroy() and also before
> ->destroy():
>
Except, the failed init path does not call qdisc_destroy.
static struct Qdisc *qdisc_create(struct net_device *dev,
[...]
if (ops->init) {
err = ops->init(sch, tca[TCA_OPTIONS]);
if (err != 0)
goto err_out5;
}
[...]
err_out5:
/* ops->init() failed, we call ->destroy() like qdisc_create_dflt() */
if (ops->destroy)
ops->destroy(sch);
err_out3:
dev_put(dev);
kfree((char *) sch - sch->padded);
err_out2:
module_put(ops->owner);
err_out:
*errp = err;
return NULL;
[...]
>
> void qdisc_destroy(struct Qdisc *qdisc)
> {
> const struct Qdisc_ops *ops = qdisc->ops;
> struct sk_buff *skb, *tmp;
>
> if (qdisc->flags & TCQ_F_BUILTIN ||
> !refcount_dec_and_test(&qdisc->refcnt))
> return;
>
> #ifdef CONFIG_NET_SCHED
> qdisc_hash_del(qdisc);
>
> qdisc_put_stab(rtnl_dereference(qdisc->stab));
> #endif
> gen_kill_estimator(&qdisc->rate_est);
> if (ops->reset)
> ops->reset(qdisc);
> if (ops->destroy)
> ops->destroy(qdisc);
>
