From: kuznet@ms2.inr.ac.ru
To: mostrows@speakeasy.net
Cc: davem@redhat.com, linux-kernel@vger.kernel.org,
linux-net@vger.kernel.org, netdev@oss.sgi.com
Subject: Re: [PATCH] PPPOE can kfree SKB twice (was Re: kernel panic problem. (smp, iptables?))
Date: Thu, 19 Jul 2001 22:17:52 +0400 (MSK DST) [thread overview]
Message-ID: <200107191817.WAA32355@ms2.inr.ac.ru> (raw)
In-Reply-To: <sb666cohk89.fsf@slug.watson.ibm.com> from "Michal Ostrowski" at Jul 19, 1 02:00:54 pm
Hello!
> However, could we not have dev_queue_xmit behave as such (not free
> frame on failure)?
If you need to hold original skb, you may hold its refcnt.
However, this feature inevitably results in big troubles: dev_queue_xmit()
is allowed to change skb and you cannot assume anything about this.
So that resuing skb dev_queue_xmit() is fatal bug not depending on anything.
> The reason why I'm proposing this is that ppp_generic.c assumes that
> the skb is still available after a transmission failure via pppoe. To
> support the semantics of dev_queue_xmit and ppp_generic we would have
> to always copy skb's inside pppoe_xmit. Then, if dev_queue_xmit fails
> the original is deleted.
You need not copy it. I said "clone".
Nobody is allowed to touch _data_ part of skb, so that you need not
to copy data.
Alexey
next prev parent reply other threads:[~2001-07-19 18:18 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-07-17 2:35 kernel panic problem. (smp, iptables?) Andrew Friedley
2001-07-18 3:58 ` [PATCH] PPPOE can kfree SKB twice (was Re: kernel panic problem. (smp, iptables?)) David S. Miller
2001-07-18 14:23 ` Michal Ostrowski
2001-07-19 12:30 ` Michal Ostrowski
2001-07-19 17:27 ` kuznet
2001-07-19 18:00 ` Michal Ostrowski
2001-07-19 18:17 ` kuznet [this message]
2001-07-19 18:57 ` Michal Ostrowski
2001-07-19 23:13 ` David S. Miller
2001-07-19 23:53 ` Andrew Friedley
2001-07-20 7:13 ` Rainer Clasen
2001-07-20 7:28 ` David S. Miller
2001-07-20 15:36 ` Rainer Clasen
2001-07-09 11:51 ` [OOPS] network related crash with Linux 2.4 Moritz Schulte
2001-07-10 5:19 ` Rainer Clasen
2001-08-01 20:21 ` Rainer Clasen
2001-07-22 2:07 ` kernel panic problem. (smp, iptables?) Rusty Russell
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