netdev - [PATCH net 2/2] mptcp: revert "mptcp: provide subflow aware release function"

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Date:   Thu,  1 Apr 2021 18:57:45 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     netdev@...r.kernel.org
Cc:     mptcp@...ts.linux.dev, "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net 2/2] mptcp: revert "mptcp: provide subflow aware release function"

This change reverts commit ad98dd37051e ("mptcp: provide subflow aware
release function"). The latter introduced a deadlock spotted by
syzkaller and is not needed anymore after the previous commit.

Fixes: ad98dd37051e ("mptcp: provide subflow aware release function")
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
 net/mptcp/protocol.c | 55 ++------------------------------------------
 1 file changed, 2 insertions(+), 53 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index e06cea0a3c54..4bde960e19dc 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -11,7 +11,6 @@
 #include <linux/netdevice.h>
 #include <linux/sched/signal.h>
 #include <linux/atomic.h>
-#include <linux/igmp.h>
 #include <net/sock.h>
 #include <net/inet_common.h>
 #include <net/inet_hashtables.h>
@@ -20,7 +19,6 @@
 #include <net/tcp_states.h>
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 #include <net/transp_v6.h>
-#include <net/addrconf.h>
 #endif
 #include <net/mptcp.h>
 #include <net/xfrm.h>
@@ -3464,34 +3462,10 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
 	return mask;
 }
 
-static int mptcp_release(struct socket *sock)
-{
-	struct mptcp_subflow_context *subflow;
-	struct sock *sk = sock->sk;
-	struct mptcp_sock *msk;
-
-	if (!sk)
-		return 0;
-
-	lock_sock(sk);
-
-	msk = mptcp_sk(sk);
-
-	mptcp_for_each_subflow(msk, subflow) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-
-		ip_mc_drop_socket(ssk);
-	}
-
-	release_sock(sk);
-
-	return inet_release(sock);
-}
-
 static const struct proto_ops mptcp_stream_ops = {
 	.family		   = PF_INET,
 	.owner		   = THIS_MODULE,
-	.release	   = mptcp_release,
+	.release	   = inet_release,
 	.bind		   = mptcp_bind,
 	.connect	   = mptcp_stream_connect,
 	.socketpair	   = sock_no_socketpair,
@@ -3583,35 +3557,10 @@ void __init mptcp_proto_init(void)
 }
 
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
-static int mptcp6_release(struct socket *sock)
-{
-	struct mptcp_subflow_context *subflow;
-	struct mptcp_sock *msk;
-	struct sock *sk = sock->sk;
-
-	if (!sk)
-		return 0;
-
-	lock_sock(sk);
-
-	msk = mptcp_sk(sk);
-
-	mptcp_for_each_subflow(msk, subflow) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-
-		ip_mc_drop_socket(ssk);
-		ipv6_sock_mc_close(ssk);
-		ipv6_sock_ac_close(ssk);
-	}
-
-	release_sock(sk);
-	return inet6_release(sock);
-}
-
 static const struct proto_ops mptcp_v6_stream_ops = {
 	.family		   = PF_INET6,
 	.owner		   = THIS_MODULE,
-	.release	   = mptcp6_release,
+	.release	   = inet6_release,
 	.bind		   = mptcp_bind,
 	.connect	   = mptcp_stream_connect,
 	.socketpair	   = sock_no_socketpair,
-- 
2.26.2