From: Paolo Abeni <pabeni@xxxxxxxxxx>
Christoph reports a lockdep splat in the mptcp_subflow_create_socket()
error path, when such function is invoked by
mptcp_pm_nl_create_listen_socket().
Such code path acquires two separates, nested socket lock, with the
internal lock operation lacking the "nested" annotation. Adding that
in sock_release() for mptcp's sake only could be confusing.
Instead just add a new lockclass to the in-kernel msk socket,
re-initializing the lockdep infra after the socket creation.
Fixes: ad2171009d96 ("mptcp: fix locking for in-kernel listener creation")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Christoph Paasch <cpaasch@xxxxxxxxx>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/354
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
Tested-by: Christoph Paasch <cpaasch@xxxxxxxxx>
Signed-off-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
---
net/mptcp/pm_netlink.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 56628b52d100..5c8dea49626c 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -997,9 +997,13 @@ static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet,
return ret;
}
+static struct lock_class_key mptcp_slock_keys[2];
+static struct lock_class_key mptcp_keys[2];
+
static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
struct mptcp_pm_addr_entry *entry)
{
+ bool is_ipv6 = sk->sk_family == AF_INET6;
int addrlen = sizeof(struct sockaddr_in);
struct sockaddr_storage addr;
struct socket *ssock;
@@ -1016,6 +1020,18 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
if (!newsk)
return -EINVAL;
+ /* The subflow socket lock is acquired in a nested to the msk one
+ * in several places, even by the TCP stack, and this msk is a kernel
+ * socket: lockdep complains. Instead of propagating the _nested
+ * modifiers in several places, re-init the lock class for the msk
+ * socket to an mptcp specific one.
+ */
+ sock_lock_init_class_and_name(newsk,
+ is_ipv6 ? "mlock-AF_INET6" : "mlock-AF_INET",
+ &mptcp_slock_keys[is_ipv6],
+ is_ipv6 ? "msk_lock-AF_INET6" : "msk_lock-AF_INET",
+ &mptcp_keys[is_ipv6]);
+
lock_sock(newsk);
ssock = __mptcp_nmpc_socket(mptcp_sk(newsk));
release_sock(newsk);
--
2.39.2
