@@ -772,19 +772,12 @@ static void update_peercred(struct sock *sk)
static void copy_peercred(struct sock *sk, struct sock *peersk)
{
- if (sk < peersk) {
- spin_lock(&sk->sk_peer_lock);
- spin_lock_nested(&peersk->sk_peer_lock, SINGLE_DEPTH_NESTING);
- } else {
- spin_lock(&peersk->sk_peer_lock);
- spin_lock_nested(&sk->sk_peer_lock, SINGLE_DEPTH_NESTING);
- }
+ lockdep_assert_held(&unix_sk(peersk)->lock);
- sk->sk_peer_pid = get_pid(peersk->sk_peer_pid);
+ spin_lock(&sk->sk_peer_lock);
+ sk->sk_peer_pid = get_pid(peersk->sk_peer_pid);
sk->sk_peer_cred = get_cred(peersk->sk_peer_cred);
-
spin_unlock(&sk->sk_peer_lock);
- spin_unlock(&peersk->sk_peer_lock);
}
static int unix_listen(struct socket *sock, int backlog)
When (AF_UNIX, SOCK_STREAM) socket connect()s to a listening socket, the listener's sk_peer_pid/sk_peer_cred are copied to the client in copy_peercred(). Then, two sk_peer_locks are held there; one is client's and another is listener's. However, the latter is not needed because we hold the listner's unix_state_lock() there and unix_listen() cannot update the cred concurrently. Let's drop the unnecessary spin_lock() and use the bare spin_lock() for the client to protect concurrent read by getsockopt(SO_PEERCRED). Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> --- net/unix/af_unix.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-)