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mptcp: fix lockdep false positive in mptcp_pm_nl_create_listen_socket()

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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: ad2171009d ("mptcp: fix locking for in-kernel listener creation")
Cc: stable@vger.kernel.org
Reported-by: Christoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/354
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Tested-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Paolo Abeni 2023-03-09 15:50:04 +01:00 committed by Jakub Kicinski
parent 3ba1452868
commit cee4034a3d
1 changed files with 16 additions and 0 deletions
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16
net/mptcp/pm_netlink.c
View File

@ -997,9 +997,13 @@ out:
return ret; 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, static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
struct mptcp_pm_addr_entry *entry) struct mptcp_pm_addr_entry *entry)
{ {
bool is_ipv6 = sk->sk_family == AF_INET6;
int addrlen = sizeof(struct sockaddr_in); int addrlen = sizeof(struct sockaddr_in);
struct sockaddr_storage addr; struct sockaddr_storage addr;
struct socket *ssock; struct socket *ssock;
@ -1016,6 +1020,18 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
if (!newsk) if (!newsk)
return -EINVAL; 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); lock_sock(newsk);
ssock = __mptcp_nmpc_socket(mptcp_sk(newsk)); ssock = __mptcp_nmpc_socket(mptcp_sk(newsk));
release_sock(newsk); release_sock(newsk);