From mboxrd@z Thu Jan  1 00:00:00 1970
From: John Fastabend <john.fastabend@gmail.com>
Subject: Re: [RFC PATCH 15/17] net: sched: pfifo_fast use skb_array
Date: Wed, 15 Nov 2017 06:57:40 -0800
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 <20171113201235.6245.4870.stgit@john-Precision-Tower-5810>
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Cc: Daniel Borkmann <daniel@iogearbox.net>,
        Eric Dumazet <eric.dumazet@gmail.com>, make0818@gmail.com,
        Network Development <netdev@vger.kernel.org>,
        =?UTF-8?B?SmnFmcOtIFDDrXJr?= =?UTF-8?Q?o?= <jiri@resnulli.us>,
        Cong Wang <xiyou.wangcong@gmail.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
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[...]

>>  static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
>> @@ -685,17 +688,40 @@ static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
>>
>>  static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
>>  {
>> -       int prio;
>> +       unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
>>         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
>> +       int prio;
>> +
>> +       /* guard against zero length rings */
>> +       if (!qlen)
>> +               return -EINVAL;
>>
>> -       for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
>> -               qdisc_skb_head_init(band2list(priv, prio));
>> +       for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
>> +               struct skb_array *q = band2list(priv, prio);
>> +               int err;
>> +
>> +               err = skb_array_init(q, qlen, GFP_KERNEL);
>> +               if (err)
>> +                       return -ENOMEM;
> 
> This relies on the caller calling ops->destroy on error to free partially
> allocated state. For uninitialized bands, that calls spin_lock on an
> uninitialized spinlock from skb_array_cleanup -> ptr_ring_cleanup ->
> ptr_ring_consume.

Nice catch will fix in next version. And also make above suggested
changes.

Thanks,
John.