nvme-fc: cancel async events before freeing event struct

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

drivers/nvme/host/fc.c

@@ -2160,6 +2160,7 @@ nvme_fc_term_aen_ops(struct nvme_fc_ctrl *ctrl)
 	struct nvme_fc_fcp_op *aen_op;
 	int i;
 
+	cancel_work_sync(&ctrl->ctrl.async_event_work);
 	aen_op = ctrl->aen_ops;
 	for (i = 0; i < NVME_NR_AEN_COMMANDS; i++, aen_op++) {
 		__nvme_fc_exit_request(ctrl, aen_op);