From: Eric Dumazet <eric.dumazet@gmail.com>
To: Junchang Wang <junchangwang@gmail.com>
Cc: Changli Gao <xiaosuo@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Tom Herbert <therbert@google.com>, Jiri Pirko <jpirko@redhat.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Xinan Tang <xinan.tang@intel.com>,
netdev@vger.kernel.org
Subject: Re: [PATCH] net: increase skb->users instead of skb_clone()
Date: Thu, 16 Dec 2010 15:30:57 +0100 [thread overview]
Message-ID: <1292509857.2883.190.camel@edumazet-laptop> (raw)
In-Reply-To: <AANLkTim--M0TvW9oUi0UO6Ej_8aLezneQsdRx7X0CXDt@mail.gmail.com>
Le jeudi 16 décembre 2010 à 22:20 +0800, Junchang Wang a écrit :
> On Thu, Dec 16, 2010 at 3:23 PM, Changli Gao <xiaosuo@gmail.com> wrote:
>
> >> You beat me, but I was thinking of a different way, adding a new
> >> pt_prev->xmit_func(), handling all the details (no need for atomic ops
> >> on skb users if packet is not delivered at all).
> >>
> >> By the way, your patch is not 100% safe/OK, because af_packet rcv()
> >> handler writes on skb (skb_pull() and all)
> >>
> >
> > But af_packet_rcv() restores skbs at last.
> >
> > if (skb_head != skb->data && skb_shared(skb)) {
> > skb->data = skb_head;
> > skb->len = skb_len;
> > }
> >
> If af packet_rcv invokes skb_clone, this skb is differ from the original one.
> Eric's warning is right.
It was a false alarm.
If packet_rcv() invokes skb_clone(), skb still points to original skb.
No worry.
next prev parent reply other threads:[~2010-12-16 14:31 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-16 5:57 [PATCH] net: increase skb->users instead of skb_clone() Changli Gao
2010-12-16 7:18 ` Eric Dumazet
2010-12-16 7:23 ` Changli Gao
2010-12-16 7:50 ` Eric Dumazet
2010-12-16 14:20 ` Junchang Wang
2010-12-16 14:30 ` Eric Dumazet [this message]
2010-12-16 14:05 ` Junchang Wang
2010-12-16 14:12 ` Changli Gao
2010-12-16 14:36 ` Junchang Wang
2010-12-16 14:18 ` Eric Dumazet
2010-12-16 14:31 ` Junchang Wang
2010-12-16 14:41 ` Eric Dumazet
2010-12-16 14:43 ` Changli Gao
2010-12-17 0:24 ` Junchang Wang
2010-12-20 5:50 ` David Miller
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