nvme-tcp: cancel async events before freeing event struct

Cancel async event work in case async event has been queued up, and
nvme_tcp_submit_async_event() runs after event has been freed.
Signed-off-by: David Milburn <dmilburn@redhat.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/tcp.c

@@ -1597,6 +1597,7 @@ static struct blk_mq_tag_set *nvme_tcp_alloc_tagset(struct nvme_ctrl *nctrl,
 static void nvme_tcp_free_admin_queue(struct nvme_ctrl *ctrl)
 {
 	if (to_tcp_ctrl(ctrl)->async_req.pdu) {
+		cancel_work_sync(&ctrl->async_event_work);
 		nvme_tcp_free_async_req(to_tcp_ctrl(ctrl));
 		to_tcp_ctrl(ctrl)->async_req.pdu = NULL;
 	}