netdev - [PATCH net-next] inet: use call_rcu_hurry() in inet_free

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Message-ID: <20240426070202.1267739-1-edumazet@google.com>
Date: Fri, 26 Apr 2024 07:02:02 +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>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] inet: use call_rcu_hurry() in inet_free_ifa()

This is a followup of commit c4e86b4363ac ("net: add two more
call_rcu_hurry()")

Our reference to ifa->ifa_dev must be freed ASAP
to release the reference to the netdev the same way.

inet_rcu_free_ifa()

	in_dev_put()
	 -> in_dev_finish_destroy()
	   -> netdev_put()

This should speedup device/netns dismantles when CONFIG_RCU_LAZY=y

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/devinet.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 7592f242336b7fdf67e79dbd75407cf03e841cfc..364dbf0cd9bf2f6e96a221317c88dad965209659 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -224,6 +224,7 @@ static struct in_ifaddr *inet_alloc_ifa(void)
 static void inet_rcu_free_ifa(struct rcu_head *head)
 {
 	struct in_ifaddr *ifa = container_of(head, struct in_ifaddr, rcu_head);
+
 	if (ifa->ifa_dev)
 		in_dev_put(ifa->ifa_dev);
 	kfree(ifa);
@@ -231,7 +232,11 @@ static void inet_rcu_free_ifa(struct rcu_head *head)
 
 static void inet_free_ifa(struct in_ifaddr *ifa)
 {
-	call_rcu(&ifa->rcu_head, inet_rcu_free_ifa);
+	/* Our reference to ifa->ifa_dev must be freed ASAP
+	 * to release the reference to the netdev the same way.
+	 * in_dev_put() -> in_dev_finish_destroy() -> netdev_put()
+	 */
+	call_rcu_hurry(&ifa->rcu_head, inet_rcu_free_ifa);
 }
 
 static void in_dev_free_rcu(struct rcu_head *head)
-- 
2.44.0.769.g3c40516874-goog