From: Longpeng(Mike) longpeng2@huawei.com
[ Upstream commit 49b0b6ffe20c5344f4173f3436298782a08da4f2 ]
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.
Fixes: 0ea9e1d3a9e3 ("VSOCK: Introduce virtio_transport.ko") Cc: Stefan Hajnoczi stefanha@redhat.com Signed-off-by: Longpeng(Mike) longpeng2@huawei.com Reviewed-by: Stefano Garzarella sgarzare@redhat.com Link: https://lore.kernel.org/r/20210812053056.1699-1-longpeng2@huawei.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/vmw_vsock/virtio_transport.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c index 2700a63ab095..3a056f8affd1 100644 --- a/net/vmw_vsock/virtio_transport.c +++ b/net/vmw_vsock/virtio_transport.c @@ -356,11 +356,14 @@ 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->sk_error_report(sk); - release_sock(sk); }
static void virtio_vsock_update_guest_cid(struct virtio_vsock *vsock)