netdev - [PATCH net-next] ipv6: anycast: use call_rcu_hurry() in aca

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Date: Mon, 29 Apr 2024 18:36:43 +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] ipv6: anycast: use call_rcu_hurry() in aca_put()

This is a followup of commit b5327b9a300e ("ipv6: use
call_rcu_hurry() in fib6_info_release()").

I had another pmtu.sh failure, and found another lazy
call_rcu() causing this failure.

aca_free_rcu() calls fib6_info_release() which releases
devices references.

We must not delay it too much or risk unregister_netdevice/ref_tracker
traces because references to netdev are not released in time.

This should speedup device/netns dismantles when CONFIG_RCU_LAZY=y

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv6/anycast.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/ipv6/anycast.c b/net/ipv6/anycast.c
index 0f2506e3535925468dcc5fa6cc30ae0952a67ea7..0627c4c18d1a5067a668da778ad444855194cbeb 100644
--- a/net/ipv6/anycast.c
+++ b/net/ipv6/anycast.c
@@ -252,9 +252,8 @@ static void aca_free_rcu(struct rcu_head *h)
 
 static void aca_put(struct ifacaddr6 *ac)
 {
-	if (refcount_dec_and_test(&ac->aca_refcnt)) {
-		call_rcu(&ac->rcu, aca_free_rcu);
-	}
+	if (refcount_dec_and_test(&ac->aca_refcnt))
+		call_rcu_hurry(&ac->rcu, aca_free_rcu);
 }
 
 static struct ifacaddr6 *aca_alloc(struct fib6_info *f6i,
-- 
2.44.0.769.g3c40516874-goog