[patch net-next v2 08/11] ipv4: fib: Allow for consistent FIB dumping
From: Jiri Pirko <jiri@resnulli.us>
Date: 2016-11-23 14:34:42
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
From: Ido Schimmel <redacted> The next patch will enable listeners of the FIB notification chain to request a dump of the FIB tables. However, since RTNL isn't taken during the dump, it's possible for the FIB tables to change mid-dump, which will result in inconsistency between the listener's table and the kernel's. Allow listeners to know about changes that occurred mid-dump, by adding a change sequence counter to each net namespace. The counter is incremented just before a notification is sent in the FIB chain. Signed-off-by: Ido Schimmel <redacted> Signed-off-by: Jiri Pirko <redacted> --- include/net/netns/ipv4.h | 2 ++ net/ipv4/fib_frontend.c | 2 ++ net/ipv4/fib_trie.c | 1 + 3 files changed, 5 insertions(+)
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 7adf438..d236c08 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h@@ -136,5 +136,7 @@ struct netns_ipv4 { int sysctl_fib_multipath_use_neigh; #endif atomic_t rt_genid; + + atomic_t fib_seq; }; #endif
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 121384b..cf8c867 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c@@ -1219,6 +1219,8 @@ static int __net_init ip_fib_net_init(struct net *net) int err; size_t size = sizeof(struct hlist_head) * FIB_TABLE_HASHSZ; + atomic_set(&net->ipv4.fib_seq, 0); + /* Avoid false sharing : Use at least a full cache line */ size = max_t(size_t, size, L1_CACHE_BYTES);
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 9bfce0d..b1d2d09 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c@@ -101,6 +101,7 @@ EXPORT_SYMBOL(unregister_fib_notifier); int call_fib_notifiers(struct net *net, enum fib_event_type event_type, struct fib_notifier_info *info) { + atomic_inc(&net->ipv4.fib_seq); info->net = net; return atomic_notifier_call_chain(&fib_chain, event_type, info); }
--
2.7.4