RDMA/core: Trigger a WARN_ON if the driver causes uobjects to become leaked

Drivers that fail destroy can cause uverbs to leak uobjects. Drivers are
required to always eventually destroy their ubojects, so trigger a WARN_ON
to detect this driver bug.

Link: https://lore.kernel.org/r/0-v1-b1e0ed400ba9+f7-warn_destroy_ufile_hw_jgg@nvidia.comReviewed-by: NLeon Romanovsky <leonro@nvidia.com>
Reviewed-by: NGal Pressman <galpress@amazon.com>
Signed-off-by: NJason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/rdma_core.c

@@ -895,8 +895,9 @@ void uverbs_destroy_ufile_hw(struct ib_uverbs_file *ufile,
 		if (__uverbs_cleanup_ufile(ufile, reason)) {
 			/*
 			 * No entry was cleaned-up successfully during this
-			 * iteration
+			 * iteration. It is a driver bug to fail destruction.
 			 */
+			WARN_ON(!list_empty(&ufile->uobjects));
 			break;
 		}