From 35d7c70870338aa6a367b9e4ed528914320b0be0 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Wed, 22 Oct 2025 05:39:46 +0000 Subject: neighbour: Annotate access to neigh_parms fields. NEIGH_VAR() is read locklessly in the fast path, and IPv6 ndisc uses NEIGH_VAR_SET() locklessly. The next patch will convert neightbl_dump_info() to RCU. Let's annotate accesses to neigh_param with READ_ONCE() and WRITE_ONCE(). Note that ndisc_ifinfo_sysctl_change() uses &NEIGH_VAR() and we cannot use '&' with READ_ONCE(), so NEIGH_VAR_PTR() is introduced. Note also that NEIGH_VAR_INIT() does not need WRITE_ONCE() as it is before parms is published. Also, the only user hippi_neigh_setup_dev() is no longer called since commit e3804cbebb67 ("net: remove COMPAT_NET_DEV_OPS"), which looks wrong, but probably no one uses HIPPI and RoadRunner. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20251022054004.2514876-3-kuniyu@google.com Signed-off-by: Jakub Kicinski --- include/net/neighbour.h | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/include/net/neighbour.h b/include/net/neighbour.h index 4a30bd458c5a..998ff9eccebb 100644 --- a/include/net/neighbour.h +++ b/include/net/neighbour.h @@ -92,15 +92,17 @@ struct neigh_parms { static inline void neigh_var_set(struct neigh_parms *p, int index, int val) { set_bit(index, p->data_state); - p->data[index] = val; + WRITE_ONCE(p->data[index], val); } -#define NEIGH_VAR(p, attr) ((p)->data[NEIGH_VAR_ ## attr]) +#define __NEIGH_VAR(p, attr) ((p)->data[NEIGH_VAR_ ## attr]) +#define NEIGH_VAR(p, attr) READ_ONCE(__NEIGH_VAR(p, attr)) +#define NEIGH_VAR_PTR(p, attr) (&(__NEIGH_VAR(p, attr))) /* In ndo_neigh_setup, NEIGH_VAR_INIT should be used. * In other cases, NEIGH_VAR_SET should be used. */ -#define NEIGH_VAR_INIT(p, attr, val) (NEIGH_VAR(p, attr) = val) +#define NEIGH_VAR_INIT(p, attr, val) (__NEIGH_VAR(p, attr) = val) #define NEIGH_VAR_SET(p, attr, val) neigh_var_set(p, NEIGH_VAR_ ## attr, val) static inline void neigh_parms_data_state_setall(struct neigh_parms *p) @@ -378,6 +380,13 @@ struct net *neigh_parms_net(const struct neigh_parms *parms) unsigned long neigh_rand_reach_time(unsigned long base); +static inline void neigh_set_reach_time(struct neigh_parms *p) +{ + unsigned long base = NEIGH_VAR(p, BASE_REACHABLE_TIME); + + WRITE_ONCE(p->reachable_time, neigh_rand_reach_time(base)); +} + void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p, struct sk_buff *skb); struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl, struct net *net, -- cgit v1.2.3 From 3064d0fe02af23a3956d2b690461abb44da88cf4 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Wed, 22 Oct 2025 05:39:49 +0000 Subject: neighbour: Convert rwlock of struct neigh_table to spinlock. Only neigh_for_each() and neigh_seq_start/stop() are on the reader side of neigh_table.lock. Let's convert rwlock to the plain spinlock. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20251022054004.2514876-6-kuniyu@google.com Signed-off-by: Jakub Kicinski --- include/net/neighbour.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/net/neighbour.h b/include/net/neighbour.h index 998ff9eccebb..2dfee6d4258a 100644 --- a/include/net/neighbour.h +++ b/include/net/neighbour.h @@ -238,7 +238,7 @@ struct neigh_table { atomic_t gc_entries; struct list_head gc_list; struct list_head managed_list; - rwlock_t lock; + spinlock_t lock; unsigned long last_rand; struct neigh_statistics __percpu *stats; struct neigh_hash_table __rcu *nht; -- cgit v1.2.3