On Wed, Feb 08, 2017 at 11:16:39AM +0100, Jiri Pirko wrote:
> From: Ido Schimmel <ido...@mellanox.com>
>
> When a multipath route is hit the kernel doesn't consider nexthops that
> are DEAD or LINKDOWN when IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN is set.
> Devices that offload multipath routes need to be made aware of nexthop
> status changes. Otherwise, the device will keep forwarding packets to
> non-functional nexthops.
>
> Add the FIB_EVENT_NH_{ADD,DEL} events to the fib notification chain,
> which notify capable devices when they should add or delete a nexthop
> from their tables.
This looks good -- thanks for doing this.
IIUC the hardware forwarding use case for your hardware covered by David
Ahern's patch[1] to the ipv4 software path selection is already covered,
so this is probably the last known link/neighbor forwarding issue for
ipv4 that needs coverage.
1. a6db449 net: ipv4: Consider failed nexthops in multipath routes
> Cc: Roopa Prabhu <ro...@cumulusnetworks.com>
> Cc: David Ahern <d...@cumulusnetworks.com>
> Cc: Andy Gospodarek <a...@greyhouse.net>
Reviewed-by: Andy Gospodarek <go...@broadcom.com>
> Signed-off-by: Ido Schimmel <ido...@mellanox.com>
> Signed-off-by: Jiri Pirko <j...@mellanox.com>
> ---
> include/net/ip_fib.h | 7 +++++++
> net/ipv4/fib_semantics.c | 33 +++++++++++++++++++++++++++++++++
> 2 files changed, 40 insertions(+)
>
> diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
> index 57c2a86..45a184e 100644
> --- a/include/net/ip_fib.h
> +++ b/include/net/ip_fib.h
> @@ -214,11 +214,18 @@ struct fib_entry_notifier_info {
> u32 nlflags;
> };
>
> +struct fib_nh_notifier_info {
> + struct fib_notifier_info info; /* must be first */
> + struct fib_nh *fib_nh;
> +};
> +
> enum fib_event_type {
> FIB_EVENT_ENTRY_ADD,
> FIB_EVENT_ENTRY_DEL,
> FIB_EVENT_RULE_ADD,
> FIB_EVENT_RULE_DEL,
> + FIB_EVENT_NH_ADD,
> + FIB_EVENT_NH_DEL,
> };
>
> int register_fib_notifier(struct notifier_block *nb,
> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> index 6306a67..317026a 100644
> --- a/net/ipv4/fib_semantics.c
> +++ b/net/ipv4/fib_semantics.c
> @@ -1355,6 +1355,36 @@ int fib_sync_down_addr(struct net_device *dev, __be32
> local)
> return ret;
> }
>
> +static int call_fib_nh_notifiers(struct fib_nh *fib_nh,
> + enum fib_event_type event_type)
> +{
> + struct in_device *in_dev = __in_dev_get_rtnl(fib_nh->nh_dev);
> + struct fib_nh_notifier_info info = {
> + .fib_nh = fib_nh,
> + };
> +
> + switch (event_type) {
> + case FIB_EVENT_NH_ADD:
> + if (fib_nh->nh_flags & RTNH_F_DEAD)
> + break;
> + if (IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
> + fib_nh->nh_flags & RTNH_F_LINKDOWN)
> + break;
> + return call_fib_notifiers(dev_net(fib_nh->nh_dev), event_type,
> + &info.info);
> + case FIB_EVENT_NH_DEL:
> + if ((IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
> + fib_nh->nh_flags & RTNH_F_LINKDOWN) ||
> + (fib_nh->nh_flags & RTNH_F_DEAD))
> + return call_fib_notifiers(dev_net(fib_nh->nh_dev),
> + event_type, &info.info);
> + default:
> + break;
> + }
> +
> + return NOTIFY_DONE;
> +}
> +
> /* 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
> @@ -1396,6 +1426,8 @@ int fib_sync_down_dev(struct net_device *dev, unsigned
> long event, bool force)
> nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
> break;
> }
> + call_fib_nh_notifiers(nexthop_nh,
> + FIB_EVENT_NH_DEL);
> dead++;
> }
> #ifdef CONFIG_IP_ROUTE_MULTIPATH
> @@ -1550,6 +1582,7 @@ int fib_sync_up(struct net_device *dev, unsigned int
> nh_flags)
> continue;
> alive++;
> nexthop_nh->nh_flags &= ~nh_flags;
> + call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
> } endfor_nexthops(fi)
>
> if (alive > 0) {
> --
> 2.7.4
>
