From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 03C32C43143 for ; Tue, 2 Oct 2018 03:24:31 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9B10020652 for ; Tue, 2 Oct 2018 03:24:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9B10020652 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 42PPdm58w0zF3F6 for ; Tue, 2 Oct 2018 13:24:28 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=ozlabs.ru (client-ip=107.173.13.209; helo=ozlabs.ru; envelope-from=aik@ozlabs.ru; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Received: from ozlabs.ru (unknown [107.173.13.209]) by lists.ozlabs.org (Postfix) with ESMTP id 42PPbd1yMgzF3Cw for ; Tue, 2 Oct 2018 13:22:37 +1000 (AEST) Received: from vpl1.ozlabs.ibm.com (localhost [IPv6:::1]) by ozlabs.ru (Postfix) with ESMTP id DA909AE8001F; Mon, 1 Oct 2018 23:20:50 -0400 (EDT) From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Subject: [RFC PATCH kernel] vfio/spapr_tce: Get rid of possible infinite loop Date: Tue, 2 Oct 2018 13:22:31 +1000 Message-Id: <20181002032231.7494-1-aik@ozlabs.ru> X-Mailer: git-send-email 2.11.0 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexey Kardashevskiy , Alex Williamson , kvm-ppc@vger.kernel.org, David Gibson Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" As a part of cleanup, the SPAPR TCE IOMMU subdriver releases preregistered memory. If there is a bug in memory release, the loop in tce_iommu_release() becomes infinite; this actually happened to me. This makes the loop finite and prints a warning on every failure to make the code more bug prone. Signed-off-by: Alexey Kardashevskiy --- drivers/vfio/vfio_iommu_spapr_tce.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c index b1a8ab3..ece0651 100644 --- a/drivers/vfio/vfio_iommu_spapr_tce.c +++ b/drivers/vfio/vfio_iommu_spapr_tce.c @@ -371,6 +371,7 @@ static void tce_iommu_release(void *iommu_data) { struct tce_container *container = iommu_data; struct tce_iommu_group *tcegrp; + struct tce_iommu_prereg *tcemem, *tmtmp; long i; while (tce_groups_attached(container)) { @@ -393,13 +394,8 @@ static void tce_iommu_release(void *iommu_data) tce_iommu_free_table(container, tbl); } - while (!list_empty(&container->prereg_list)) { - struct tce_iommu_prereg *tcemem; - - tcemem = list_first_entry(&container->prereg_list, - struct tce_iommu_prereg, next); - WARN_ON_ONCE(tce_iommu_prereg_free(container, tcemem)); - } + list_for_each_entry_safe(tcemem, tmtmp, &container->prereg_list, next) + WARN_ON(tce_iommu_prereg_free(container, tcemem)); tce_iommu_disable(container); if (container->mm) -- 2.11.0