netdev - Re: [PATCH] net: move "IPv6: sending pkt_too

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Message-ID: <20120729122402.GA23910@spike.0x539.de>
Date:	Sun, 29 Jul 2012 14:24:02 +0200
From:	Philipp Kern <pkern@...ian.org>
To:	Joe Perches <joe@...ches.com>
Cc:	linux-kernel@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>, netdev@...r.kernel.org,
	ak@...ux.intel.com
Subject: Re: [PATCH] net: move "IPv6: sending pkt_too_big to self" to NETDEBUG

On Sat, Jul 28, 2012 at 10:29:20AM -0700, Joe Perches wrote:
> On Sat, 2012-07-28 at 17:06 +0200, Philipp Kern wrote:
> > ip6_xmit checks if the outgoing packet is larger than the path MTU and
> > emits ICMPv6 packet too big locally if this is the case. Logging this,
> > even at KERN_DEBUG, confuses users. It is also not actually helpful for
> > debugging, given that there is no reference to the connection that
> > triggered this event.
> []
> > diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> []
> > @@ -241,7 +241,7 @@ int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
> >  			       dst->dev, dst_output);
> >  	}
> >  
> > -	net_dbg_ratelimited("IPv6: sending pkt_too_big to self\n");
> > +	LIMIT_NETDEBUG("IPv6: sending pkt_too_big to self\n");
> LIMIT_NETDEBUG doesn't include a logging level.
> Add a KERN_DEBUG prefix or another KERN_<LEVEL>.

True, sorry, and thanks. That got lost with the change to net_dbg_ratelimited.

> Maybe it'd be better to add the context too.

Right. What kind of context do you want to see? Would saddr, daddr and dst_mtu
be enough? What about skb->len / local_df / skb_is_gso (which are in the
condition of the preceding if)?

Kind regards
Philipp Kern

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