linux-kernel - Re: [patch net-next v2] ipv6: log autoconfiguration failures

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Date:	Wed, 11 Dec 2013 20:21:38 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Denys Vlasenko <dvlasenk@...hat.com>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	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>, jpirko@...hat.com
Subject: Re: [patch net-next v2] ipv6: log autoconfiguration failures

On Wed, Dec 11, 2013 at 12:45:14PM +0100, Denys Vlasenko wrote:
> If ipv6 auto-configuration does not work, currently it's hard
> to track what's going on. This change adds log messages
> (at debug level) on every code path where ipv6 autoconf fails.
> 
> v2: fixed indentation in multi-line log output statements.

Have you seen lots of those problems? Some of those seem like very
serious problems and maybe could also deserve a pr_warn or pr_err.

I hope these are one-time errors, so I don't think counters would
be helpful.

> Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
> ---
>  net/ipv6/addrconf.c | 45 ++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 36 insertions(+), 9 deletions(-)
> 
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index 3c3425e..c09c5f4 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -1694,8 +1694,11 @@ static void addrconf_leave_anycast(struct inet6_ifaddr *ifp)
>  
>  static int addrconf_ifid_eui48(u8 *eui, struct net_device *dev)
>  {
> -	if (dev->addr_len != ETH_ALEN)
> +	if (dev->addr_len != ETH_ALEN) {
> +		pr_debug("IPv6 addrconf: %s: address length %d != %s\n",
> +			 dev->name, dev->addr_len, "ETH_ALEN");

I like __stringify(ETH_ALEN) instead of "ETH_ALEN" a bit more but no need
to change the patch because of that. ;)

> @@ -1842,6 +1865,10 @@ static int ipv6_inherit_eui64(u8 *eui, struct inet6_dev *idev)
>  		}
>  	}
>  	read_unlock_bh(&idev->lock);
> +	if (err)
> +		pr_debug("IPv6 addrconf: "
> +			 "%s: no link-local address to inherit\n",
> +			 idev->dev->name);

Another nit:
String literals should not be wrapped to ease grepping for them in the source.

Thanks,

  Hannes

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