[PATCH v2 net-next 0/5] ipv6: cleanup after rt6_genid removal

[PATCH v2 net-next 0/5] ipv6: cleanup after rt6_genid removal

[Hannes Frederic Sowa]

Leftover patches after rt6_genid removal after 705f1c869d577c ("ipv6:
remove rt6i_genid").

Major two changes are:
* keep fib6_sernum per namespace to reduce number of flushes in case
  system has high number of namespaces
* make fn_sernum updates cheaper

v2: Incorporated feedback from Cong Wang, thanks a lot!

Hannes Frederic Sowa (5):
  ipv6: minor fib6 cleanups like type safety, bool conversion, inline
    removal
  ipv6: make rt_sernum atomic and serial number fields ordinary ints
  ipv6: only generate one new serial number per fib mutation
  ipv6: make fib6 serial number per namespace
  ipv6: don't walk node's leaf during serial number update

 include/net/ip6_fib.h    |  20 +++++--
 include/net/netns/ipv6.h |   2 +-
 net/ipv6/af_inet6.c      |   2 +-
 net/ipv6/ip6_fib.c       | 142 ++++++++++++++++++++++++-----------------------
 4 files changed, 91 insertions(+), 75 deletions(-)

-- 
1.9.3

[PATCH v2 net-next 1/5] ipv6: minor fib6 cleanups like type safety, bool conversion, inline removal

[Hannes Frederic Sowa]

Also renamed struct fib6_walker_t to fib6_walker and enum fib_walk_state_t
to fib6_walk_state as recommended by Cong Wang.

Cc: Cong Wang <cwang@twopensource.com>
Cc: YOSHIFUJI Hideaki <hideaki@yoshifuji.org>
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
 include/net/ip6_fib.h | 18 ++++++++++---
 net/ipv6/ip6_fib.c    | 71 ++++++++++++++++++++++-----------------------------
 2 files changed, 45 insertions(+), 44 deletions(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index cf485f9..9221bf4 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -202,15 +202,25 @@ static inline void ip6_rt_put(struct rt6_info *rt)
 	dst_release(&rt->dst);
 }
 
-struct fib6_walker_t {
+enum fib6_walk_state {
+#ifdef CONFIG_IPV6_SUBTREES
+	FWS_S,
+#endif
+	FWS_L,
+	FWS_R,
+	FWS_C,
+	FWS_U
+};
+
+struct fib6_walker {
 	struct list_head lh;
 	struct fib6_node *root, *node;
 	struct rt6_info *leaf;
-	unsigned char state;
-	unsigned char prune;
+	enum fib6_walk_state state;
+	bool prune;
 	unsigned int skip;
 	unsigned int count;
-	int (*func)(struct fib6_walker_t *);
+	int (*func)(struct fib6_walker *);
 	void *args;
 };
 
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 97b9fa8..e8d7465 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -46,18 +46,8 @@
 
 static struct kmem_cache *fib6_node_kmem __read_mostly;
 
-enum fib_walk_state_t {
-#ifdef CONFIG_IPV6_SUBTREES
-	FWS_S,
-#endif
-	FWS_L,
-	FWS_R,
-	FWS_C,
-	FWS_U
-};
-
-struct fib6_cleaner_t {
-	struct fib6_walker_t w;
+struct fib6_cleaner {
+	struct fib6_walker w;
 	struct net *net;
 	int (*func)(struct rt6_info *, void *arg);
 	void *arg;
@@ -74,8 +64,8 @@ static DEFINE_RWLOCK(fib6_walker_lock);
 static void fib6_prune_clones(struct net *net, struct fib6_node *fn);
 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn);
 static struct fib6_node *fib6_repair_tree(struct net *net, struct fib6_node *fn);
-static int fib6_walk(struct fib6_walker_t *w);
-static int fib6_walk_continue(struct fib6_walker_t *w);
+static int fib6_walk(struct fib6_walker *w);
+static int fib6_walk_continue(struct fib6_walker *w);
 
 /*
  *	A routing update causes an increase of the serial number on the
@@ -91,20 +81,21 @@ static void fib6_gc_timer_cb(unsigned long arg);
 static LIST_HEAD(fib6_walkers);
 #define FOR_WALKERS(w) list_for_each_entry(w, &fib6_walkers, lh)
 
-static inline void fib6_walker_link(struct fib6_walker_t *w)
+static void fib6_walker_link(struct fib6_walker *w)
 {
 	write_lock_bh(&fib6_walker_lock);
 	list_add(&w->lh, &fib6_walkers);
 	write_unlock_bh(&fib6_walker_lock);
 }
 
-static inline void fib6_walker_unlink(struct fib6_walker_t *w)
+static void fib6_walker_unlink(struct fib6_walker *w)
 {
 	write_lock_bh(&fib6_walker_lock);
 	list_del(&w->lh);
 	write_unlock_bh(&fib6_walker_lock);
 }
-static __inline__ u32 fib6_new_sernum(void)
+
+static u32 fib6_new_sernum(void)
 {
 	u32 n = ++rt_sernum;
 	if ((__s32)n <= 0)
@@ -128,7 +119,7 @@ static __inline__ u32 fib6_new_sernum(void)
 # define BITOP_BE32_SWIZZLE	0
 #endif
 
-static __inline__ __be32 addr_bit_set(const void *token, int fn_bit)
+static __be32 addr_bit_set(const void *token, int fn_bit)
 {
 	const __be32 *addr = token;
 	/*
@@ -142,7 +133,7 @@ static __inline__ __be32 addr_bit_set(const void *token, int fn_bit)
 	       addr[fn_bit >> 5];
 }
 
-static __inline__ struct fib6_node *node_alloc(void)
+static struct fib6_node *node_alloc(void)
 {
 	struct fib6_node *fn;
 
@@ -151,12 +142,12 @@ static __inline__ struct fib6_node *node_alloc(void)
 	return fn;
 }
 
-static __inline__ void node_free(struct fib6_node *fn)
+static void node_free(struct fib6_node *fn)
 {
 	kmem_cache_free(fib6_node_kmem, fn);
 }
 
-static __inline__ void rt6_release(struct rt6_info *rt)
+static void rt6_release(struct rt6_info *rt)
 {
 	if (atomic_dec_and_test(&rt->rt6i_ref))
 		dst_free(&rt->dst);
@@ -267,7 +258,7 @@ static void __net_init fib6_tables_init(struct net *net)
 
 #endif
 
-static int fib6_dump_node(struct fib6_walker_t *w)
+static int fib6_dump_node(struct fib6_walker *w)
 {
 	int res;
 	struct rt6_info *rt;
@@ -287,7 +278,7 @@ static int fib6_dump_node(struct fib6_walker_t *w)
 
 static void fib6_dump_end(struct netlink_callback *cb)
 {
-	struct fib6_walker_t *w = (void *)cb->args[2];
+	struct fib6_walker *w = (void *)cb->args[2];
 
 	if (w) {
 		if (cb->args[4]) {
@@ -310,7 +301,7 @@ static int fib6_dump_done(struct netlink_callback *cb)
 static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
 			   struct netlink_callback *cb)
 {
-	struct fib6_walker_t *w;
+	struct fib6_walker *w;
 	int res;
 
 	w = (void *)cb->args[2];
@@ -355,7 +346,7 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 	unsigned int h, s_h;
 	unsigned int e = 0, s_e;
 	struct rt6_rtnl_dump_arg arg;
-	struct fib6_walker_t *w;
+	struct fib6_walker *w;
 	struct fib6_table *tb;
 	struct hlist_head *head;
 	int res = 0;
@@ -627,7 +618,7 @@ insert_above:
 	return ln;
 }
 
-static inline bool rt6_qualify_for_ecmp(struct rt6_info *rt)
+static bool rt6_qualify_for_ecmp(struct rt6_info *rt)
 {
 	return (rt->rt6i_flags & (RTF_GATEWAY|RTF_ADDRCONF|RTF_DYNAMIC)) ==
 	       RTF_GATEWAY;
@@ -820,7 +811,7 @@ add:
 	return 0;
 }
 
-static __inline__ void fib6_start_gc(struct net *net, struct rt6_info *rt)
+static void fib6_start_gc(struct net *net, struct rt6_info *rt)
 {
 	if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
 	    (rt->rt6i_flags & (RTF_EXPIRES | RTF_CACHE)))
@@ -1174,7 +1165,7 @@ static struct fib6_node *fib6_repair_tree(struct net *net,
 	int children;
 	int nstate;
 	struct fib6_node *child, *pn;
-	struct fib6_walker_t *w;
+	struct fib6_walker *w;
 	int iter = 0;
 
 	for (;;) {
@@ -1276,7 +1267,7 @@ static struct fib6_node *fib6_repair_tree(struct net *net,
 static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
 			   struct nl_info *info)
 {
-	struct fib6_walker_t *w;
+	struct fib6_walker *w;
 	struct rt6_info *rt = *rtp;
 	struct net *net = info->nl_net;
 
@@ -1414,7 +1405,7 @@ int fib6_del(struct rt6_info *rt, struct nl_info *info)
  *	<0  -> walk is terminated by an error.
  */
 
-static int fib6_walk_continue(struct fib6_walker_t *w)
+static int fib6_walk_continue(struct fib6_walker *w)
 {
 	struct fib6_node *fn, *pn;
 
@@ -1498,7 +1489,7 @@ skip:
 	}
 }
 
-static int fib6_walk(struct fib6_walker_t *w)
+static int fib6_walk(struct fib6_walker *w)
 {
 	int res;
 
@@ -1512,11 +1503,11 @@ static int fib6_walk(struct fib6_walker_t *w)
 	return res;
 }
 
-static int fib6_clean_node(struct fib6_walker_t *w)
+static int fib6_clean_node(struct fib6_walker *w)
 {
 	int res;
 	struct rt6_info *rt;
-	struct fib6_cleaner_t *c = container_of(w, struct fib6_cleaner_t, w);
+	struct fib6_cleaner *c = container_of(w, struct fib6_cleaner, w);
 	struct nl_info info = {
 		.nl_net = c->net,
 	};
@@ -1554,9 +1545,9 @@ static int fib6_clean_node(struct fib6_walker_t *w)
 
 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
 			    int (*func)(struct rt6_info *, void *arg),
-			    int prune, void *arg)
+			    bool prune, void *arg)
 {
-	struct fib6_cleaner_t c;
+	struct fib6_cleaner c;
 
 	c.w.root = root;
 	c.w.func = fib6_clean_node;
@@ -1583,7 +1574,7 @@ void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *arg),
 		hlist_for_each_entry_rcu(table, head, tb6_hlist) {
 			write_lock_bh(&table->tb6_lock);
 			fib6_clean_tree(net, &table->tb6_root,
-					func, 0, arg);
+					func, false, arg);
 			write_unlock_bh(&table->tb6_lock);
 		}
 	}
@@ -1602,7 +1593,7 @@ static int fib6_prune_clone(struct rt6_info *rt, void *arg)
 
 static void fib6_prune_clones(struct net *net, struct fib6_node *fn)
 {
-	fib6_clean_tree(net, fn, fib6_prune_clone, 1, NULL);
+	fib6_clean_tree(net, fn, fib6_prune_clone, true, NULL);
 }
 
 static int fib6_update_sernum(struct rt6_info *rt, void *arg)
@@ -1828,7 +1819,7 @@ void fib6_gc_cleanup(void)
 
 struct ipv6_route_iter {
 	struct seq_net_private p;
-	struct fib6_walker_t w;
+	struct fib6_walker w;
 	loff_t skip;
 	struct fib6_table *tbl;
 	__u32 sernum;
@@ -1859,7 +1850,7 @@ static int ipv6_route_seq_show(struct seq_file *seq, void *v)
 	return 0;
 }
 
-static int ipv6_route_yield(struct fib6_walker_t *w)
+static int ipv6_route_yield(struct fib6_walker *w)
 {
 	struct ipv6_route_iter *iter = w->args;
 
@@ -1980,7 +1971,7 @@ static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
 
 static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
 {
-	struct fib6_walker_t *w = &iter->w;
+	struct fib6_walker *w = &iter->w;
 	return w->node && !(w->state == FWS_U && w->node == w->root);
 }
 
-- 
1.9.3

[PATCH v2 net-next 2/5] ipv6: make rt_sernum atomic and serial number fields ordinary ints

[Hannes Frederic Sowa]

Cc: YOSHIFUJI Hideaki <hideaki@yoshifuji.org>
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
 include/net/ip6_fib.h |  2 +-
 net/ipv6/ip6_fib.c    | 23 +++++++++++++----------
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 9221bf4..8eea35d 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -64,7 +64,7 @@ struct fib6_node {
 
 	__u16			fn_bit;		/* bit key */
 	__u16			fn_flags;
-	__u32			fn_sernum;
+	int			fn_sernum;
 	struct rt6_info		*rr_ptr;
 };
 
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index e8d7465..332f1e0 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -74,7 +74,7 @@ static int fib6_walk_continue(struct fib6_walker *w);
  *	result of redirects, path MTU changes, etc.
  */
 
-static __u32 rt_sernum;
+static atomic_t rt_sernum = ATOMIC_INIT(1);
 
 static void fib6_gc_timer_cb(unsigned long arg);
 
@@ -95,12 +95,15 @@ static void fib6_walker_unlink(struct fib6_walker *w)
 	write_unlock_bh(&fib6_walker_lock);
 }
 
-static u32 fib6_new_sernum(void)
+static int fib6_new_sernum(void)
 {
-	u32 n = ++rt_sernum;
-	if ((__s32)n <= 0)
-		rt_sernum = n = 1;
-	return n;
+	int new, old;
+
+	do {
+		old = atomic_read(&rt_sernum);
+		new = old < INT_MAX ? old + 1 : 1;
+	} while (atomic_cmpxchg(&rt_sernum, old, new) != old);
+	return new;
 }
 
 /*
@@ -421,7 +424,7 @@ static struct fib6_node *fib6_add_1(struct fib6_node *root,
 	struct rt6key *key;
 	int	bit;
 	__be32	dir = 0;
-	__u32	sernum = fib6_new_sernum();
+	int	sernum = fib6_new_sernum();
 
 	RT6_TRACE("fib6_add_1\n");
 
@@ -1598,7 +1601,7 @@ static void fib6_prune_clones(struct net *net, struct fib6_node *fn)
 
 static int fib6_update_sernum(struct rt6_info *rt, void *arg)
 {
-	__u32 sernum = *(__u32 *)arg;
+	int sernum = *(int *)arg;
 
 	if (rt->rt6i_node &&
 	    rt->rt6i_node->fn_sernum != sernum)
@@ -1609,7 +1612,7 @@ static int fib6_update_sernum(struct rt6_info *rt, void *arg)
 
 static void fib6_flush_trees(struct net *net)
 {
-	__u32 new_sernum = fib6_new_sernum();
+	int new_sernum = fib6_new_sernum();
 
 	fib6_clean_all(net, fib6_update_sernum, &new_sernum);
 }
@@ -1822,7 +1825,7 @@ struct ipv6_route_iter {
 	struct fib6_walker w;
 	loff_t skip;
 	struct fib6_table *tbl;
-	__u32 sernum;
+	int sernum;
 };
 
 static int ipv6_route_seq_show(struct seq_file *seq, void *v)
-- 
1.9.3

[PATCH v2 net-next 3/5] ipv6: only generate one new serial number per fib mutation

[Hannes Frederic Sowa]

Cc: YOSHIFUJI Hideaki <hideaki@yoshifuji.org>
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
 net/ipv6/ip6_fib.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 332f1e0..be9cb09 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -417,14 +417,13 @@ out:
 static struct fib6_node *fib6_add_1(struct fib6_node *root,
 				     struct in6_addr *addr, int plen,
 				     int offset, int allow_create,
-				     int replace_required)
+				     int replace_required, int sernum)
 {
 	struct fib6_node *fn, *in, *ln;
 	struct fib6_node *pn = NULL;
 	struct rt6key *key;
 	int	bit;
 	__be32	dir = 0;
-	int	sernum = fib6_new_sernum();
 
 	RT6_TRACE("fib6_add_1\n");
 
@@ -842,6 +841,7 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info,
 	int err = -ENOMEM;
 	int allow_create = 1;
 	int replace_required = 0;
+	int sernum = fib6_new_sernum();
 
 	if (info->nlh) {
 		if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
@@ -854,7 +854,7 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info,
 
 	fn = fib6_add_1(root, &rt->rt6i_dst.addr, rt->rt6i_dst.plen,
 			offsetof(struct rt6_info, rt6i_dst), allow_create,
-			replace_required);
+			replace_required, sernum);
 	if (IS_ERR(fn)) {
 		err = PTR_ERR(fn);
 		fn = NULL;
@@ -888,14 +888,14 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info,
 			sfn->leaf = info->nl_net->ipv6.ip6_null_entry;
 			atomic_inc(&info->nl_net->ipv6.ip6_null_entry->rt6i_ref);
 			sfn->fn_flags = RTN_ROOT;
-			sfn->fn_sernum = fib6_new_sernum();
+			sfn->fn_sernum = sernum;
 
 			/* Now add the first leaf node to new subtree */
 
 			sn = fib6_add_1(sfn, &rt->rt6i_src.addr,
 					rt->rt6i_src.plen,
 					offsetof(struct rt6_info, rt6i_src),
-					allow_create, replace_required);
+					allow_create, replace_required, sernum);
 
 			if (IS_ERR(sn)) {
 				/* If it is failed, discard just allocated
@@ -914,7 +914,7 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info,
 			sn = fib6_add_1(fn->subtree, &rt->rt6i_src.addr,
 					rt->rt6i_src.plen,
 					offsetof(struct rt6_info, rt6i_src),
-					allow_create, replace_required);
+					allow_create, replace_required, sernum);
 
 			if (IS_ERR(sn)) {
 				err = PTR_ERR(sn);
-- 
1.9.3

[PATCH v2 net-next 4/5] ipv6: make fib6 serial number per namespace

[Hannes Frederic Sowa]

Try to reduce number of possible fn_sernum mutation by constraining them
to their namespace.

Also remove rt_genid which I forgot to remove in 705f1c869d577c ("ipv6:
remove rt6i_genid").

Cc: YOSHIFUJI Hideaki <hideaki@yoshifuji.org>
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
 include/net/netns/ipv6.h |  2 +-
 net/ipv6/af_inet6.c      |  2 +-
 net/ipv6/ip6_fib.c       | 13 ++++++-------
 3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
index eade27a..69ae41f 100644
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -76,7 +76,7 @@ struct netns_ipv6 {
 #endif
 #endif
 	atomic_t		dev_addr_genid;
-	atomic_t		rt_genid;
+	atomic_t		fib6_sernum;
 };
 
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 34f726f..e8c4400 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -766,7 +766,7 @@ static int __net_init inet6_net_init(struct net *net)
 	net->ipv6.sysctl.icmpv6_time = 1*HZ;
 	net->ipv6.sysctl.flowlabel_consistency = 1;
 	net->ipv6.sysctl.auto_flowlabels = 0;
-	atomic_set(&net->ipv6.rt_genid, 0);
+	atomic_set(&net->ipv6.fib6_sernum, 1);
 
 	err = ipv6_init_mibs(net);
 	if (err)
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index be9cb09..6f9beb1 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -74,8 +74,6 @@ static int fib6_walk_continue(struct fib6_walker *w);
  *	result of redirects, path MTU changes, etc.
  */
 
-static atomic_t rt_sernum = ATOMIC_INIT(1);
-
 static void fib6_gc_timer_cb(unsigned long arg);
 
 static LIST_HEAD(fib6_walkers);
@@ -95,14 +93,15 @@ static void fib6_walker_unlink(struct fib6_walker *w)
 	write_unlock_bh(&fib6_walker_lock);
 }
 
-static int fib6_new_sernum(void)
+static int fib6_new_sernum(struct net *net)
 {
 	int new, old;
 
 	do {
-		old = atomic_read(&rt_sernum);
+		old = atomic_read(&net->ipv6.fib6_sernum);
 		new = old < INT_MAX ? old + 1 : 1;
-	} while (atomic_cmpxchg(&rt_sernum, old, new) != old);
+	} while (atomic_cmpxchg(&net->ipv6.fib6_sernum,
+				old, new) != old);
 	return new;
 }
 
@@ -841,7 +840,7 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info,
 	int err = -ENOMEM;
 	int allow_create = 1;
 	int replace_required = 0;
-	int sernum = fib6_new_sernum();
+	int sernum = fib6_new_sernum(info->nl_net);
 
 	if (info->nlh) {
 		if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
@@ -1612,7 +1611,7 @@ static int fib6_update_sernum(struct rt6_info *rt, void *arg)
 
 static void fib6_flush_trees(struct net *net)
 {
-	int new_sernum = fib6_new_sernum();
+	int new_sernum = fib6_new_sernum(net);
 
 	fib6_clean_all(net, fib6_update_sernum, &new_sernum);
 }
-- 
1.9.3

[PATCH v2 net-next 5/5] ipv6: don't walk node's leaf during serial number update

[Hannes Frederic Sowa]

Cc: YOSHIFUJI Hideaki <hideaki@yoshifuji.org>
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
 net/ipv6/ip6_fib.c | 47 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 30 insertions(+), 17 deletions(-)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 6f9beb1..b2d1838 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -50,6 +50,7 @@ struct fib6_cleaner {
 	struct fib6_walker w;
 	struct net *net;
 	int (*func)(struct rt6_info *, void *arg);
+	int sernum;
 	void *arg;
 };
 
@@ -105,6 +106,10 @@ static int fib6_new_sernum(struct net *net)
 	return new;
 }
 
+enum {
+	FIB6_NO_SERNUM_CHANGE = 0,
+};
+
 /*
  *	Auxiliary address test functions for the radix tree.
  *
@@ -1514,6 +1519,16 @@ static int fib6_clean_node(struct fib6_walker *w)
 		.nl_net = c->net,
 	};
 
+	if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
+	    w->node->fn_sernum != c->sernum)
+		w->node->fn_sernum = c->sernum;
+
+	if (!c->func) {
+		WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
+		w->leaf = NULL;
+		return 0;
+	}
+
 	for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
 		res = c->func(rt, c->arg);
 		if (res < 0) {
@@ -1547,7 +1562,7 @@ static int fib6_clean_node(struct fib6_walker *w)
 
 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
 			    int (*func)(struct rt6_info *, void *arg),
-			    bool prune, void *arg)
+			    bool prune, int sernum, void *arg)
 {
 	struct fib6_cleaner c;
 
@@ -1557,14 +1572,16 @@ static void fib6_clean_tree(struct net *net, struct fib6_node *root,
 	c.w.count = 0;
 	c.w.skip = 0;
 	c.func = func;
+	c.sernum = sernum;
 	c.arg = arg;
 	c.net = net;
 
 	fib6_walk(&c.w);
 }
 
-void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *arg),
-		    void *arg)
+static void __fib6_clean_all(struct net *net,
+			     int (*func)(struct rt6_info *, void *),
+			     int sernum, void *arg)
 {
 	struct fib6_table *table;
 	struct hlist_head *head;
@@ -1576,13 +1593,19 @@ void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *arg),
 		hlist_for_each_entry_rcu(table, head, tb6_hlist) {
 			write_lock_bh(&table->tb6_lock);
 			fib6_clean_tree(net, &table->tb6_root,
-					func, false, arg);
+					func, false, sernum, arg);
 			write_unlock_bh(&table->tb6_lock);
 		}
 	}
 	rcu_read_unlock();
 }
 
+void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *),
+		    void *arg)
+{
+	__fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg);
+}
+
 static int fib6_prune_clone(struct rt6_info *rt, void *arg)
 {
 	if (rt->rt6i_flags & RTF_CACHE) {
@@ -1595,25 +1618,15 @@ static int fib6_prune_clone(struct rt6_info *rt, void *arg)
 
 static void fib6_prune_clones(struct net *net, struct fib6_node *fn)
 {
-	fib6_clean_tree(net, fn, fib6_prune_clone, true, NULL);
-}
-
-static int fib6_update_sernum(struct rt6_info *rt, void *arg)
-{
-	int sernum = *(int *)arg;
-
-	if (rt->rt6i_node &&
-	    rt->rt6i_node->fn_sernum != sernum)
-		rt->rt6i_node->fn_sernum = sernum;
-
-	return 0;
+	fib6_clean_tree(net, fn, fib6_prune_clone, true,
+			FIB6_NO_SERNUM_CHANGE, NULL);
 }
 
 static void fib6_flush_trees(struct net *net)
 {
 	int new_sernum = fib6_new_sernum(net);
 
-	fib6_clean_all(net, fib6_update_sernum, &new_sernum);
+	__fib6_clean_all(net, NULL, new_sernum, NULL);
 }
 
 /*
-- 
1.9.3

Re: [PATCH v2 net-next 0/5] ipv6: cleanup after rt6_genid removal

[David Miller]

From: Hannes Frederic Sowa <hannes@stressinduktion.org>
Date: Mon,  6 Oct 2014 19:58:33 +0200

> Leftover patches after rt6_genid removal after 705f1c869d577c ("ipv6:
> remove rt6i_genid").
> 
> Major two changes are:
> * keep fib6_sernum per namespace to reduce number of flushes in case
>   system has high number of namespaces
> * make fn_sernum updates cheaper
> 
> v2: Incorporated feedback from Cong Wang, thanks a lot!

Series applied, thanks.