[PATCH v3 net-next 05/15] neighbour: Remove __rcu from neigh_tables[].
From: Kuniyuki Iwashima <kuniyu@google.com>
Date: 2026-08-11 02:24:56
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Since commit 1bf20cc62a54 ("neighbour: remove obsolete
EXPORT_SYMBOL()") unexported neigh_table_init(), neigh_table
cannot be registered dynamically.
Let's remove RCU protection for neigh_tables[].
Note that neightbl_set() no longer needs RCU because it holds
spin_lock_bh(&tbl->lock).
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
net/core/neighbour.c | 23 +++++++++--------------
1 file changed, 9 insertions(+), 14 deletions(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 6fda0052027b..caa52bf64a2d 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c@@ -1807,7 +1807,7 @@ void neigh_parms_release(struct neigh_table *tbl, struct neigh_parms *parms) static struct lock_class_key neigh_table_proxy_queue_class; -static struct neigh_table __rcu *neigh_tables[NEIGH_NR_TABLES] __read_mostly; +static struct neigh_table *neigh_tables[NEIGH_NR_TABLES] __read_mostly; void neigh_table_init(int index, struct neigh_table *tbl) {
@@ -1864,7 +1864,7 @@ void neigh_table_init(int index, struct neigh_table *tbl) tbl->last_flush = now; tbl->last_rand = now + tbl->parms.reachable_time * 20; - rcu_assign_pointer(neigh_tables[index], tbl); + neigh_tables[index] = tbl; } /*
@@ -1873,8 +1873,7 @@ void neigh_table_init(int index, struct neigh_table *tbl) */ int neigh_table_clear(int index, struct neigh_table *tbl) { - RCU_INIT_POINTER(neigh_tables[index], NULL); - synchronize_rcu(); + neigh_tables[index] = NULL; /* It is not clean... Fix it to unload IPv6 module safely */ cancel_delayed_work_sync(&tbl->managed_work);
@@ -1906,10 +1905,10 @@ static struct neigh_table *neigh_find_table(int family) switch (family) { case AF_INET: - tbl = rcu_dereference_rtnl(neigh_tables[NEIGH_ARP_TABLE]); + tbl = neigh_tables[NEIGH_ARP_TABLE]; break; case AF_INET6: - tbl = rcu_dereference_rtnl(neigh_tables[NEIGH_ND_TABLE]); + tbl = neigh_tables[NEIGH_ND_TABLE]; break; }
@@ -2391,10 +2390,8 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh, ndtmsg = nlmsg_data(nlh); - rcu_read_lock(); - for (tidx = 0; tidx < NEIGH_NR_TABLES; tidx++) { - tbl = rcu_dereference(neigh_tables[tidx]); + tbl = neigh_tables[tidx]; if (!tbl) continue;
@@ -2408,7 +2405,6 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh, } if (!found) { - rcu_read_unlock(); err = -ENOENT; goto errout; }
@@ -2537,7 +2533,6 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh, errout_tbl_lock: spin_unlock_bh(&tbl->lock); - rcu_read_unlock(); errout: return err; }
@@ -2589,7 +2584,7 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb) for (tidx = 0; tidx < NEIGH_NR_TABLES; tidx++) { struct neigh_parms *p; - tbl = rcu_dereference(neigh_tables[tidx]); + tbl = neigh_tables[tidx]; if (!tbl) continue;
@@ -2949,7 +2944,7 @@ static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb) rcu_read_lock(); for (t = 0; t < NEIGH_NR_TABLES; t++) { - tbl = rcu_dereference(neigh_tables[t]); + tbl = neigh_tables[t]; if (!tbl) continue;
@@ -3162,7 +3157,7 @@ int neigh_xmit(int index, struct net_device *dev, struct neighbour *neigh; rcu_read_lock(); - tbl = rcu_dereference(neigh_tables[index]); + tbl = neigh_tables[index]; if (!tbl) { rcu_read_unlock(); goto out_kfree_skb;
--
2.55.0.691.gc56d675ccc-goog