Re: [PATCH] appletalk: Set skb with destructor
[Posted July 9, 2014 by jake]
| From: |
| Eric Dumazet <eric.dumazet-AT-gmail.com> |
| To: |
| Andrey Utkin <andrey.krieger.utkin-AT-gmail.com> |
| Subject: |
| Re: [PATCH] appletalk: Set skb with destructor |
| Date: |
| Mon, 07 Jul 2014 10:57:36 +0200 |
| Message-ID: |
| <1404723456.4501.14.camel@edumazet-glaptop2.roam.corp.google.com> |
| Cc: |
| linux-kernel-AT-vger.kernel.org, kernel-janitors-AT-vger.kernel.org, acme-AT-ghostprotocols.net, netdev-AT-vger.kernel.org, davem-AT-davemloft.net |
| Archive‑link: | |
Article |
On Mon, 2014-07-07 at 11:03 +0300, Andrey Utkin wrote:
> 2014-07-07 0:42 GMT+03:00 Eric Dumazet <eric.dumazet@gmail.com>:
> >> /* Queue packet (standard) */
> >> + sock_hold(sock);
> >> + skb->destructor = atalk_skb_destructor;
> >> skb->sk = sock;
> >
> > This part is not needed : sock_queue_rcv_skb() already does the right
> > thing : It calls skb_set_owner_r(skb, sk);
> >
> > You should therefore remove the "skb->sk = sock;" line
>
> If it is so, i think this should be as another patch with its own reasoning.
>
No it is not.
Its illegal to set skb->sk to a socket without taking proper reference.
But it is useless to do this before calling sock_queue_rcv_skb(), as I
explained to you.
This is adding two extra atomic operations for nothing: skb_orphan() is
called from sock_queue_rcv_skb(), so it is kind of stupid to set a
destructor that _will_ be immediately called.
We do not do defensive programming, we try to do logical things, and
only logical things.
Please re-spin your patch, by integrating my feedback.
Thanks !
