netdev - Re: [PATCH v4] sctp: fix refcount bug in sctp

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Date:   Thu, 26 Mar 2020 09:30:08 +0800
From:   Qiujun Huang <hqjagain@...il.com>
To:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>, vyasevich@...il.com,
        nhorman@...driver.com, Jakub Kicinski <kuba@...nel.org>,
        linux-sctp@...r.kernel.org, netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, anenbupt@...il.com
Subject: Re: [PATCH v4] sctp: fix refcount bug in sctp_wfree

On Thu, Mar 26, 2020 at 8:14 AM Marcelo Ricardo Leitner
<marcelo.leitner@...il.com> wrote:
>
> On Sun, Mar 22, 2020 at 05:04:25PM +0800, Qiujun Huang wrote:
> > sctp_sock_migrate should iterate over the datamsgs to modify
> > all trunks(skbs) to newsk. For this, out_msg_list is added to
>
> s/trunks/chunks/

My :p.

>
> > sctp_outq to maintain datamsgs list.
>
> It is an interesting approach. It speeds up the migration, yes, but it
> will also use more memory per datamsg, for an operation that, when
> performed, the socket is usually calm.
>
> It's also another list to be handled, and I'm not seeing the patch
> here move the datamsg itself now to the new outq. It would need
> something along these lines:

Are all the rx chunks in the rx queues?

> sctp_sock_migrate()
> {
> ...
>         /* Move any messages in the old socket's receive queue that are for the
>          * peeled off association to the new socket's receive queue.
>          */
>         sctp_skb_for_each(skb, &oldsk->sk_receive_queue, tmp) {
>                 event = sctp_skb2event(skb);
> ...
>                 /* Walk through the pd_lobby, looking for skbs that
>                  * need moved to the new socket.
>                  */
>                 sctp_skb_for_each(skb, &oldsp->pd_lobby, tmp) {
>                         event = sctp_skb2event(skb);
>
> That said, I don't think it's worth this new list.

About this case:
datamsg
                   ->chunk0                       chunk1
       chunk2
 queue          ->transmitted                 ->retransmit
 ->not in any queue

Also need to maintain a datamsg list to record which datamsg is
processed avoiding repetitive
processing.
So, list it to outq. Maybe it will be used sometime.

>
>   Marcelo