nvme: flush reset_work before safely continuing with delete operation

Prevent racing controller reset and delete flows. reset_work must not
ever self-requeue so flushing it suffices.
Reported-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

drivers/nvme/host/core.c

@@ -102,6 +102,7 @@ static void nvme_delete_ctrl_work(struct work_struct *work)
 	struct nvme_ctrl *ctrl =
 		container_of(work, struct nvme_ctrl, delete_work);
 
+	flush_work(&ctrl->reset_work);
 	nvme_stop_ctrl(ctrl);
 	nvme_remove_namespaces(ctrl);
 	ctrl->ops->delete_ctrl(ctrl);

drivers/nvme/host/fc.c

@@ -2638,7 +2638,6 @@ nvme_fc_delete_ctrl(struct nvme_ctrl *nctrl)
 {
 	struct nvme_fc_ctrl *ctrl = to_fc_ctrl(nctrl);
 
-	cancel_work_sync(&ctrl->ctrl.reset_work);
 	cancel_delayed_work_sync(&ctrl->connect_work);
 	/*
 	 * kill the association on the link side.  this will block