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Date: Mon, 26 Oct 2015 16:31:07 -0400
From: Andy Gospodarek <gospo@...ulusnetworks.com>
To: Julian Anastasov <ja@....bg>
Cc: David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH net] ipv4: fix problems from the RTNH_F_LINKDOWN
introduction
On Sat, Oct 24, 2015 at 09:20:00PM +0300, Julian Anastasov wrote:
> When fib_netdev_event calls fib_disable_ip on NETDEV_DOWN event
> we should not delete the local routes if the local address
> is still present. The confusion comes from the fact that both
> fib_netdev_event and fib_inetaddr_event use the NETDEV_DOWN
> constant. Fix it by returning back the variable 'force'.
>
> Steps to reproduce:
> modprobe dummy
> ifconfig dummy0 192.168.168.1 up
> ip route list table local | grep dummy | grep host
> local 192.168.168.1 dev dummy0 proto kernel scope host src 192.168.168.1
I tested this before and after your patch and I don't see a different
output. Was I supposed to see something different?
> Second fix
I would prefer you move these two fixes into 2 separate patches as it
isn't totally clear which hunks fix each of these issues.
> is for fib_sync_up: when nexthop is part of multipath
> route we should clear the LINKDOWN flag when link goes UP
> or when first address is added. This is needed because we always
> set LINKDOWN flag when DEAD flag is set but now the nexthop
> is not dead anymore. Examples when LINKDOWN bit can be forgotten:
>
> - link goes down (LINKDOWN is set), then link goes UP and device
> shows carrier OK but LINKDOWN remains set
>
> - last address is deleted (LINKDOWN is set), then address is
> added and device shows carrier OK but LINKDOWN remains set
Are you seeing this with iproute2 (or other tools) or are you just
seeing this by monitoring netlink messages/looking at a netlink cache
you have built inside an application?
I have seen a problem similar to what you have reported with netlink
caches and have a fix I can give you if you would like to try it. It is
a slightly larger structural change, but it appears to cover covers a
few more cases than this fix does.
>
> Fixes: 8a3d03166f19 ("net: track link-status of ipv4 nexthops")
> Signed-off-by: Julian Anastasov <ja@....bg>
> ---
> include/net/ip_fib.h | 2 +-
> net/ipv4/fib_frontend.c | 13 +++++++------
> net/ipv4/fib_semantics.c | 18 +++++++++++++++---
> 3 files changed, 23 insertions(+), 10 deletions(-)
>
> diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
> index 727d6e9..654aec1 100644
> --- a/include/net/ip_fib.h
> +++ b/include/net/ip_fib.h
> @@ -317,7 +317,7 @@ void fib_flush_external(struct net *net);
>
> /* Exported by fib_semantics.c */
> int ip_fib_check_default(__be32 gw, struct net_device *dev);
> -int fib_sync_down_dev(struct net_device *dev, unsigned long event);
> +int fib_sync_down_dev(struct net_device *dev, unsigned long event, int force);
> int fib_sync_down_addr(struct net *net, __be32 local);
> int fib_sync_up(struct net_device *dev, unsigned int nh_flags);
> void fib_select_multipath(struct fib_result *res);
> diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
> index 690bcbc..4826a22 100644
> --- a/net/ipv4/fib_frontend.c
> +++ b/net/ipv4/fib_frontend.c
> @@ -1110,9 +1110,10 @@ static void nl_fib_lookup_exit(struct net *net)
> net->ipv4.fibnl = NULL;
> }
>
> -static void fib_disable_ip(struct net_device *dev, unsigned long event)
> +static void fib_disable_ip(struct net_device *dev, unsigned long event,
> + int force)
> {
> - if (fib_sync_down_dev(dev, event))
> + if (fib_sync_down_dev(dev, event, force))
> fib_flush(dev_net(dev));
> rt_cache_flush(dev_net(dev));
> arp_ifdown(dev);
> @@ -1140,7 +1141,7 @@ static int fib_inetaddr_event(struct notifier_block *this, unsigned long event,
> /* Last address was deleted from this interface.
> * Disable IP.
> */
> - fib_disable_ip(dev, event);
> + fib_disable_ip(dev, event, 1);
> } else {
> rt_cache_flush(dev_net(dev));
> }
> @@ -1157,7 +1158,7 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo
> unsigned int flags;
>
> if (event == NETDEV_UNREGISTER) {
> - fib_disable_ip(dev, event);
> + fib_disable_ip(dev, event, 2);
> rt_flush_dev(dev);
> return NOTIFY_DONE;
> }
> @@ -1178,14 +1179,14 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo
> rt_cache_flush(net);
> break;
> case NETDEV_DOWN:
> - fib_disable_ip(dev, event);
> + fib_disable_ip(dev, event, 0);
> break;
> case NETDEV_CHANGE:
> flags = dev_get_flags(dev);
> if (flags & (IFF_RUNNING | IFF_LOWER_UP))
> fib_sync_up(dev, RTNH_F_LINKDOWN);
> else
> - fib_sync_down_dev(dev, event);
> + fib_sync_down_dev(dev, event, 0);
> /* fall through */
> case NETDEV_CHANGEMTU:
> rt_cache_flush(net);
> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> index 064bd3c..f657418 100644
> --- a/net/ipv4/fib_semantics.c
> +++ b/net/ipv4/fib_semantics.c
> @@ -1281,7 +1281,13 @@ int fib_sync_down_addr(struct net *net, __be32 local)
> return ret;
> }
>
> -int fib_sync_down_dev(struct net_device *dev, unsigned long event)
> +/* Event force Flags Description
> + * NETDEV_CHANGE 0 LINKDOWN Carrier OFF, not for scope host
> + * NETDEV_DOWN 0 LINKDOWN|DEAD Link down, not for scope host
> + * NETDEV_DOWN 1 LINKDOWN|DEAD Last address removed
> + * NETDEV_UNREGISTER 2 LINKDOWN|DEAD Device removed
> + */
> +int fib_sync_down_dev(struct net_device *dev, unsigned long event, int force)
> {
> int ret = 0;
> int scope = RT_SCOPE_NOWHERE;
> @@ -1290,8 +1296,7 @@ int fib_sync_down_dev(struct net_device *dev, unsigned long event)
> struct hlist_head *head = &fib_info_devhash[hash];
> struct fib_nh *nh;
>
> - if (event == NETDEV_UNREGISTER ||
> - event == NETDEV_DOWN)
> + if (force)
> scope = -1;
>
> hlist_for_each_entry(nh, head, nh_hash) {
> @@ -1440,6 +1445,13 @@ int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
> if (!(dev->flags & IFF_UP))
> return 0;
>
> + if (nh_flags & RTNH_F_DEAD) {
> + unsigned int flags = dev_get_flags(dev);
> +
> + if (flags & (IFF_RUNNING | IFF_LOWER_UP))
> + nh_flags |= RTNH_F_LINKDOWN;
> + }
> +
> prev_fi = NULL;
> hash = fib_devindex_hashfn(dev->ifindex);
> head = &fib_info_devhash[hash];
> --
> 1.9.3
>
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