[PATCH rcu/dev 2/3] net: Use call_rcu_flush() for in_dev_rcu_put

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
To: linux-kernel@vger.kernel.org
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	David Ahern <dsahern@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Jakub Kicinski <kuba@kernel.org>,
	Jamal Hadi Salim <jhs@mojatatu.com>,
	Jiri Pirko <jiri@resnulli.us>,
	netdev@vger.kernel.org, Paolo Abeni <pabeni@redhat.com>,
	rcu@vger.kernel.org, rostedt@goodmis.org, paulmck@kernel.org,
	fweisbec@gmail.com
Subject: [PATCH rcu/dev 2/3] net: Use call_rcu_flush() for in_dev_rcu_put
Date: Thu, 17 Nov 2022 03:15:49 +0000	[thread overview]
Message-ID: <20221117031551.1142289-2-joel@joelfernandes.org> (raw)
In-Reply-To: <20221117031551.1142289-1-joel@joelfernandes.org>

In a networking test on ChromeOS, we find that using the new CONFIG_RCU_LAZY
causes a networking test to fail in the teardown phase.

The failure happens during: ip netns del <name>

Using ftrace, I found the callbacks it was queuing which this series fixes. Use
call_rcu_flush() to revert to the old behavior. With that, the test passes.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 net/ipv4/devinet.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index e8b9a9202fec..98b20f333e00 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -328,7 +328,7 @@ static void inetdev_destroy(struct in_device *in_dev)
 	neigh_parms_release(&arp_tbl, in_dev->arp_parms);
 	arp_ifdown(dev);
 
-	call_rcu(&in_dev->rcu_head, in_dev_rcu_put);
+	call_rcu_flush(&in_dev->rcu_head, in_dev_rcu_put);
 }
 
 int inet_addr_onlink(struct in_device *in_dev, __be32 a, __be32 b)
-- 
2.38.1.584.g0f3c55d4c2-goog

