netdev - [RFC PATCH net-next 11/19] ipv6: Add explicit flush indication to routes

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Message-Id: <20171231161513.25785-12-idosch@mellanox.com>
Date:   Sun, 31 Dec 2017 18:15:05 +0200
From:   Ido Schimmel <idosch@...lanox.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, dsahern@...il.com, roopa@...ulusnetworks.com,
        nicolas.dichtel@...nd.com, mlxsw@...lanox.com,
        Ido Schimmel <idosch@...lanox.com>
Subject: [RFC PATCH net-next 11/19] ipv6: Add explicit flush indication to routes

When routes that are a part of a multipath route are evaluated by
fib6_ifdown() in response to NETDEV_DOWN and NETDEV_UNREGISTER events
the state of their sibling routes is not considered.

This will change in subsequent patches in order to align IPv6 with
IPv4's behavior. For example, when the last sibling in a multipath route
becomes dead, the entire multipath route needs to be removed.

To prevent the tree walker from re-evaluating all the sibling routes
each time, we can simply evaluate them once - when the first sibling is
traversed.

If we determine the entire multipath route needs to be removed, then the
'should_flush' bit is set in all the siblings, which will cause the
walker to flush them when it traverses them.

Signed-off-by: Ido Schimmel <idosch@...lanox.com>
---
 include/net/ip6_fib.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 44d96a91e745..affea1aa6ae4 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -173,7 +173,8 @@ struct rt6_info {
 	unsigned short			rt6i_nfheader_len;
 	u8				rt6i_protocol;
 	u8				exception_bucket_flushed:1,
-					unused:7;
+					should_flush:1,
+					unused:6;
 };

 #define for_each_fib6_node_rt_rcu(fn)					\
-- 
2.14.3