netdev - [PATCH net-next 5/5] net: do not acquire rtnl in fib_seq

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Message-ID: <20241009184405.3752829-6-edumazet@google.com>
Date: Wed,  9 Oct 2024 18:44:05 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: David Ahern <dsahern@...nel.org>, Kuniyuki Iwashima <kuniyu@...zon.com>, Jiri Pirko <jiri@...nulli.us>, 
	netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 5/5] net: do not acquire rtnl in fib_seq_sum()

After we made sure no fib_seq_read() handlers needs RTNL anymore,
we can remove RTNL from fib_seq_sum().

Note that after RTNL was dropped, fib_seq_sum() result was possibly
outdated anyway.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/net/fib_notifier.h | 2 +-
 net/core/fib_notifier.c    | 2 --
 net/ipv4/fib_notifier.c    | 2 +-
 net/ipv4/ipmr.c            | 2 +-
 net/ipv6/fib6_notifier.c   | 2 +-
 net/ipv6/ip6mr.c           | 2 +-
 6 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/include/net/fib_notifier.h b/include/net/fib_notifier.h
index 6d59221ff05ad605dea6bf0e5f3d6b9d24237537..48aad6128feab6452c91e11ec31f9f1f238032d8 100644
--- a/include/net/fib_notifier.h
+++ b/include/net/fib_notifier.h
@@ -28,7 +28,7 @@ enum fib_event_type {
 struct fib_notifier_ops {
 	int family;
 	struct list_head list;
-	unsigned int (*fib_seq_read)(struct net *net);
+	unsigned int (*fib_seq_read)(const struct net *net);
 	int (*fib_dump)(struct net *net, struct notifier_block *nb,
 			struct netlink_ext_ack *extack);
 	struct module *owner;
diff --git a/net/core/fib_notifier.c b/net/core/fib_notifier.c
index fc96259807b62fd2b41c47f385d7db23a7e38186..5cdca49b1d7c1cc9097c6a9fe93fae701c54eaca 100644
--- a/net/core/fib_notifier.c
+++ b/net/core/fib_notifier.c
@@ -43,7 +43,6 @@ static unsigned int fib_seq_sum(struct net *net)
 	struct fib_notifier_ops *ops;
 	unsigned int fib_seq = 0;
 
-	rtnl_lock();
 	rcu_read_lock();
 	list_for_each_entry_rcu(ops, &fn_net->fib_notifier_ops, list) {
 		if (!try_module_get(ops->owner))
@@ -52,7 +51,6 @@ static unsigned int fib_seq_sum(struct net *net)
 		module_put(ops->owner);
 	}
 	rcu_read_unlock();
-	rtnl_unlock();
 
 	return fib_seq;
 }
diff --git a/net/ipv4/fib_notifier.c b/net/ipv4/fib_notifier.c
index 21c85c80de641112d66a28645b1fb17c7071863f..b1551c26554b79b70a29c9fab7f5ba8d7c0049c5 100644
--- a/net/ipv4/fib_notifier.c
+++ b/net/ipv4/fib_notifier.c
@@ -27,7 +27,7 @@ int call_fib4_notifiers(struct net *net, enum fib_event_type event_type,
 	return call_fib_notifiers(net, event_type, info);
 }
 
-static unsigned int fib4_seq_read(struct net *net)
+static unsigned int fib4_seq_read(const struct net *net)
 {
 	/* Paired with WRITE_ONCE() in call_fib4_notifiers() */
 	return READ_ONCE(net->ipv4.fib_seq) + fib4_rules_seq_read(net);
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 35ed0316518424c7742a93bd72d56295e1eb01aa..7a95daeb1946ad2f9c6d00a75469e37f92dddf9c 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -3035,7 +3035,7 @@ static const struct net_protocol pim_protocol = {
 };
 #endif
 
-static unsigned int ipmr_seq_read(struct net *net)
+static unsigned int ipmr_seq_read(const struct net *net)
 {
 	return READ_ONCE(net->ipv4.ipmr_seq) + ipmr_rules_seq_read(net);
 }
diff --git a/net/ipv6/fib6_notifier.c b/net/ipv6/fib6_notifier.c
index f87ae33e1d01f4e8d55f2af435bd8eff72bd9ea6..949b72610df704b6afe455daf0d680dbe4504e87 100644
--- a/net/ipv6/fib6_notifier.c
+++ b/net/ipv6/fib6_notifier.c
@@ -22,7 +22,7 @@ int call_fib6_notifiers(struct net *net, enum fib_event_type event_type,
 	return call_fib_notifiers(net, event_type, info);
 }
 
-static unsigned int fib6_seq_read(struct net *net)
+static unsigned int fib6_seq_read(const struct net *net)
 {
 	return fib6_tables_seq_read(net) + fib6_rules_seq_read(net);
 }
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 3f9501fd8c1ae583d4862128e8620ce6cc114d25..9528e17665fdb0ce4be07c76703ba74f06386370 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -1260,7 +1260,7 @@ static int ip6mr_device_event(struct notifier_block *this,
 	return NOTIFY_DONE;
 }
 
-static unsigned int ip6mr_seq_read(struct net *net)
+static unsigned int ip6mr_seq_read(const struct net *net)
 {
 	return READ_ONCE(net->ipv6.ipmr_seq) + ip6mr_rules_seq_read(net);
 }
-- 
2.47.0.rc0.187.ge670bccf7e-goog