From: Cong Wang <xiyou.wangcong@gmail.com>
To: Xie He <xie.he.0141@gmail.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
Network Development <netdev@vger.kernel.org>,
syzbot <syzbot+4a2c52677a8a1aa283cb@syzkaller.appspotmail.com>,
William Tu <u9012063@gmail.com>
Subject: Re: [Patch net] ip_gre: set dev->hard_header_len properly
Date: Fri, 9 Oct 2020 13:38:52 -0700 [thread overview]
Message-ID: <CAM_iQpU1hU0Wg9sdTwFAG17Gk4-85+=xvZdQeb3oswhBKtAsPA@mail.gmail.com> (raw)
In-Reply-To: <CAJht_EPVyc0uAZc914E3tdgqEc7tDabpAxnBsGrRRFecc+NMwg@mail.gmail.com>
On Fri, Oct 9, 2020 at 12:51 PM Xie He <xie.he.0141@gmail.com> wrote:
>
> On Fri, Oct 9, 2020 at 12:41 PM Xie He <xie.he.0141@gmail.com> wrote:
> >
> > Thanks. But there is still something that I don't understand. What is
> > needed_headroom used for? If we are requesting space for t->encap_hlen
> > and t->tun_hlen in hard_header_len. Do we still need to use
> > needed_headroom?
>
> It seems to me that the original code includes t->encap_hlen,
> t->tun_hlen, and the IP header length in needed_headroom. (Right?) If
> we are including these in hard_header_len, we need to move them out of
> needed_headroom.
Interesting point. I think needed_headroom is 0 until we call
ipgre_changelink(), but needed_headroom is already being used
in multiple places for skb_cow_head() in the same file, I guess
they should be replaced with hard_head_len because for GRE tunnel
those are its link-layer header. What makes it more complicated
is that header_ops is actually set conditionally, so should be
hard_header_len/needed_head_room accordingly.
Thanks.
next prev parent reply other threads:[~2020-10-09 20:39 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 1:21 [Patch net] ip_gre: set dev->hard_header_len properly Cong Wang
2020-10-08 11:48 ` Willem de Bruijn
2020-10-08 17:33 ` Cong Wang
2020-10-08 19:04 ` Willem de Bruijn
2020-10-08 19:16 ` Xie He
2020-10-08 19:19 ` Willem de Bruijn
2020-10-08 20:10 ` Xie He
2020-10-08 20:31 ` Willem de Bruijn
2020-10-08 21:35 ` Xie He
2020-10-08 21:47 ` Willem de Bruijn
2020-10-08 21:54 ` Xie He
2020-10-08 23:40 ` Xie He
2020-10-09 17:43 ` Cong Wang
2020-10-09 19:41 ` Xie He
2020-10-09 19:51 ` Xie He
2020-10-09 20:38 ` Cong Wang [this message]
2020-10-10 1:07 ` Cong Wang
2020-10-10 3:10 ` Xie He
2020-10-10 18:58 ` Cong Wang
2020-10-10 21:49 ` Xie He
2020-10-11 3:55 ` Xie He
2020-10-11 14:35 ` Xie He
2020-10-08 19:18 ` Willem de Bruijn
2020-10-08 19:50 ` Cong Wang
2020-10-08 20:19 ` Willem de Bruijn
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