[patch net-next] ipv6: log autoconfiguration failures

[patch net-next] ipv6: log autoconfiguration failures

[Denys Vlasenko]

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.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.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 5087cc5..e75428f 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1692,8 +1692,11 @@ 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");
 		return -1;
+	}
 	memcpy(eui, dev->dev_addr, 3);
 	memcpy(eui + 5, dev->dev_addr + 3, 3);
 
@@ -1723,8 +1726,11 @@ static int addrconf_ifid_eui48(u8 *eui, struct net_device *dev)
 
 static int addrconf_ifid_eui64(u8 *eui, struct net_device *dev)
 {
-	if (dev->addr_len != IEEE802154_ADDR_LEN)
+	if (dev->addr_len != IEEE802154_ADDR_LEN) {
+		pr_debug("IPv6 addrconf: %s: address length %d != %s\n",
+			dev->name, dev->addr_len, "IEEE802154_ADDR_LEN");
 		return -1;
+	}
 	memcpy(eui, dev->dev_addr, 8);
 	eui[0] ^= 2;
 	return 0;
@@ -1734,8 +1740,11 @@ static int addrconf_ifid_ieee1394(u8 *eui, struct net_device *dev)
 {
 	union fwnet_hwaddr *ha;
 
-	if (dev->addr_len != FWNET_ALEN)
+	if (dev->addr_len != FWNET_ALEN) {
+		pr_debug("IPv6 addrconf: %s: address length %d != %s\n",
+			dev->name, dev->addr_len, "FWNET_ALEN");
 		return -1;
+	}
 
 	ha = (union fwnet_hwaddr *)dev->dev_addr;
 
@@ -1747,8 +1756,11 @@ static int addrconf_ifid_ieee1394(u8 *eui, struct net_device *dev)
 static int addrconf_ifid_arcnet(u8 *eui, struct net_device *dev)
 {
 	/* XXX: inherit EUI-64 from other interface -- yoshfuji */
-	if (dev->addr_len != ARCNET_ALEN)
+	if (dev->addr_len != ARCNET_ALEN) {
+		pr_debug("IPv6 addrconf: %s: address length %d != %s\n",
+			dev->name, dev->addr_len, "ARCNET_ALEN");
 		return -1;
+	}
 	memset(eui, 0, 7);
 	eui[7] = *(u8 *)dev->dev_addr;
 	return 0;
@@ -1756,17 +1768,25 @@ static int addrconf_ifid_arcnet(u8 *eui, struct net_device *dev)
 
 static int addrconf_ifid_infiniband(u8 *eui, struct net_device *dev)
 {
-	if (dev->addr_len != INFINIBAND_ALEN)
+	if (dev->addr_len != INFINIBAND_ALEN) {
+		pr_debug("IPv6 addrconf: %s: address length %d != %s\n",
+			dev->name, dev->addr_len, "INFINIBAND_ALEN");
 		return -1;
+	}
 	memcpy(eui, dev->dev_addr + 12, 8);
 	eui[0] |= 2;
 	return 0;
 }
 
-static int __ipv6_isatap_ifid(u8 *eui, __be32 addr)
+static int __ipv6_isatap_ifid(u8 *eui, struct net_device *dev)
 {
-	if (addr == 0)
+	__be32 addr = *(__be32 *)dev->dev_addr;
+
+	if (addr == 0) {
+		pr_debug("IPv6 addrconf: %s: bad dev_addr %pM\n",
+				dev->name, dev->dev_addr);
 		return -1;
+	}
 	eui[0] = (ipv4_is_zeronet(addr) || ipv4_is_private_10(addr) ||
 		  ipv4_is_loopback(addr) || ipv4_is_linklocal_169(addr) ||
 		  ipv4_is_private_172(addr) || ipv4_is_test_192(addr) ||
@@ -1783,13 +1803,14 @@ static int __ipv6_isatap_ifid(u8 *eui, __be32 addr)
 static int addrconf_ifid_sit(u8 *eui, struct net_device *dev)
 {
 	if (dev->priv_flags & IFF_ISATAP)
-		return __ipv6_isatap_ifid(eui, *(__be32 *)dev->dev_addr);
+		return __ipv6_isatap_ifid(eui, dev);
+	pr_debug("IPv6 addrconf: %s: IFF_ISATAP is unset\n", dev->name);
 	return -1;
 }
 
 static int addrconf_ifid_gre(u8 *eui, struct net_device *dev)
 {
-	return __ipv6_isatap_ifid(eui, *(__be32 *)dev->dev_addr);
+	return __ipv6_isatap_ifid(eui, dev);
 }
 
 static int addrconf_ifid_ip6tnl(u8 *eui, struct net_device *dev)
@@ -1823,6 +1844,8 @@ static int ipv6_generate_eui64(u8 *eui, struct net_device *dev)
 	case ARPHRD_TUNNEL6:
 		return addrconf_ifid_ip6tnl(eui, dev);
 	}
+	pr_debug("IPv6 addrconf: %s: dev->type %d is not supported\n",
+			dev->name, dev->type);
 	return -1;
 }
 
@@ -1840,6 +1863,10 @@ 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);
 	return err;
 }
 
-- 
1.8.1.4

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

[David Miller]

From: Denys Vlasenko <dvlasenk@redhat.com>
Date: Mon,  9 Dec 2013 17:26:48 +0100

> 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.
> 
> Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>

Add statistics, those are more globally useful.

> +		pr_debug("IPv6 addrconf: %s: address length %d != %s\n",
> +				dev->name, dev->addr_len, "ETH_ALEN");

And this is not indented correctly, the arguments on lines after the
first must line up exactly to the column after the openning parenthesis
of the function call.

The idea isn't to use just TABs until you think it looks nice, rather
you should use the appropriate number of SPACE and TAB characters
necessary to reach the exact column.