| Message ID | 20210812010939.1644-1-longpeng2@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vsock/virtio: avoid potential deadlock when vsock device remove | expand |
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c index e0c2c99..4f7c99d 100644 --- a/net/vmw_vsock/virtio_transport.c +++ b/net/vmw_vsock/virtio_transport.c @@ -357,11 +357,14 @@ static void virtio_vsock_event_fill(struct virtio_vsock *vsock) static void virtio_vsock_reset_sock(struct sock *sk) { - lock_sock(sk); + /* vmci_transport.c doesn't take sk_lock here either. At least we're + * under vsock_table_lock so the sock cannot disappear while we're + * executing. + */ + sk->sk_state = TCP_CLOSE; sk->sk_err = ECONNRESET; sk_error_report(sk); - release_sock(sk); } static void virtio_vsock_update_guest_cid(struct virtio_vsock *vsock)
There's a potential deadlock case when remove the vsock device or process the RESET event: vsock_for_each_connected_socket: spin_lock_bh(&vsock_table_lock) ----------- (1) ... virtio_vsock_reset_sock: lock_sock(sk) --------------------- (2) ... spin_unlock_bh(&vsock_table_lock) lock_sock() may do initiative schedule when the 'sk' is owned by other thread at the same time, we would receivce a warning message that "scheduling while atomic". Even worse, if the next task (selected by the scheduler) try to release a 'sk', it need to request vsock_table_lock and the deadlock occur, cause the system into softlockup state. Call trace: queued_spin_lock_slowpath vsock_remove_bound vsock_remove_sock virtio_transport_release __vsock_release vsock_release __sock_release sock_close __fput ____fput So we should not require sk_lock in this case, just like the behavior in vhost_vsock or vmci. Cc: Stefan Hajnoczi <stefanha@redhat.com> Cc: Stefano Garzarella <sgarzare@redhat.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com> --- net/vmw_vsock/virtio_transport.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)