[PATCH v3 net-next 13/15] ipmr/ip6mr: Convert net->ipv[46].ipmr_seq to atomic_t.
From: Kuniyuki Iwashima <kuniyu@google.com>
Date: 2026-02-28 22:18:25
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
We will no longer hold RTNL for ipmr_mfc_add() and ipmr_mfc_delete(). MFC entry can be loosely connected with VIF by its index for mrt->vif_table[] (stored in mfc_parent), but the two tables are not synchronised. i.e. Even if VIF 1 is removed, MFC for VIF 1 is not automatically removed. The only field that the MFC/VIF interfaces share is net->ipv[46].ipmr_seq, which is protected by RTNL. Adding a new mutex for both just to protect a single field is overkill. Let's convert the field to atomic_t. Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> --- include/linux/mroute_base.h | 8 ++++---- include/net/netns/ipv4.h | 2 +- include/net/netns/ipv6.h | 2 +- net/ipv4/ipmr.c | 4 ++-- net/ipv6/ip6mr.c | 4 ++-- 5 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/include/linux/mroute_base.h b/include/linux/mroute_base.h
index 0075f6e5c3da..0baa6f994da9 100644
--- a/include/linux/mroute_base.h
+++ b/include/linux/mroute_base.h@@ -76,7 +76,7 @@ static inline int mr_call_vif_notifiers(struct net *net, struct vif_device *vif, struct net_device *vif_dev, unsigned short vif_index, u32 tb_id, - unsigned int *ipmr_seq) + atomic_t *ipmr_seq) { struct vif_entry_notifier_info info = { .info = {
@@ -89,7 +89,7 @@ static inline int mr_call_vif_notifiers(struct net *net, }; ASSERT_RTNL(); - (*ipmr_seq)++; + atomic_inc(ipmr_seq); return call_fib_notifiers(net, event_type, &info.info); }
@@ -198,7 +198,7 @@ static inline int mr_call_mfc_notifiers(struct net *net, unsigned short family, enum fib_event_type event_type, struct mr_mfc *mfc, u32 tb_id, - unsigned int *ipmr_seq) + atomic_t *ipmr_seq) { struct mfc_entry_notifier_info info = { .info = {
@@ -209,7 +209,7 @@ static inline int mr_call_mfc_notifiers(struct net *net, }; ASSERT_RTNL(); - (*ipmr_seq)++; + atomic_inc(ipmr_seq); return call_fib_notifiers(net, event_type, &info.info); }
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 380ff34c0233..94dca64fec41 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h@@ -280,7 +280,7 @@ struct netns_ipv4 { struct fib_rules_ops *mr_rules_ops; #endif struct fib_notifier_ops *ipmr_notifier_ops; - unsigned int ipmr_seq; /* protected by rtnl_mutex */ + atomic_t ipmr_seq; #endif #ifdef CONFIG_IP_ROUTE_MULTIPATH struct sysctl_fib_multipath_hash_seed sysctl_fib_multipath_hash_seed;
diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
index 34bdb1308e8f..499e4288170f 100644
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h@@ -118,7 +118,7 @@ struct netns_ipv6 { struct seg6_pernet_data *seg6_data; struct fib_notifier_ops *notifier_ops; struct fib_notifier_ops *ip6mr_notifier_ops; - unsigned int ipmr_seq; /* protected by rtnl_mutex */ + atomic_t ipmr_seq; struct { struct hlist_head head; spinlock_t lock;
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 07f2d4f8dcbe..6ec73796d84d 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c@@ -3226,7 +3226,7 @@ static const struct net_protocol pim_protocol = { static unsigned int ipmr_seq_read(const struct net *net) { - return READ_ONCE(net->ipv4.ipmr_seq) + ipmr_rules_seq_read(net); + return atomic_read(&net->ipv4.ipmr_seq) + ipmr_rules_seq_read(net); } static int ipmr_dump(struct net *net, struct notifier_block *nb,
@@ -3247,7 +3247,7 @@ static int __net_init ipmr_notifier_init(struct net *net) { struct fib_notifier_ops *ops; - net->ipv4.ipmr_seq = 0; + atomic_set(&net->ipv4.ipmr_seq, 0); ops = fib_notifier_ops_register(&ipmr_notifier_ops_template, net); if (IS_ERR(ops))
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index e047a4680ab0..85010ff21c98 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c@@ -1280,7 +1280,7 @@ static int ip6mr_device_event(struct notifier_block *this, static unsigned int ip6mr_seq_read(const struct net *net) { - return READ_ONCE(net->ipv6.ipmr_seq) + ip6mr_rules_seq_read(net); + return atomic_read(&net->ipv6.ipmr_seq) + ip6mr_rules_seq_read(net); } static int ip6mr_dump(struct net *net, struct notifier_block *nb,
@@ -1305,7 +1305,7 @@ static int __net_init ip6mr_notifier_init(struct net *net) { struct fib_notifier_ops *ops; - net->ipv6.ipmr_seq = 0; + atomic_set(&net->ipv6.ipmr_seq, 0); ops = fib_notifier_ops_register(&ip6mr_notifier_ops_template, net); if (IS_ERR(ops))
--
2.53.0.473.g4a7958ca14-goog