From patchwork Fri Mar 13 18:36:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Logan Gunthorpe X-Patchwork-Id: 1254584 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=deltatee.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48fDtr3mccz9sP7 for ; Sat, 14 Mar 2020 05:36:52 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726526AbgCMSgv (ORCPT ); Fri, 13 Mar 2020 14:36:51 -0400 Received: from ale.deltatee.com ([207.54.116.67]:60254 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726339AbgCMSgv (ORCPT ); Fri, 13 Mar 2020 14:36:51 -0400 Received: from cgy1-donard.priv.deltatee.com ([172.16.1.31]) by ale.deltatee.com with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jCpAv-0002bu-Ds; Fri, 13 Mar 2020 12:36:50 -0600 Received: from gunthorp by cgy1-donard.priv.deltatee.com with local (Exim 4.92) (envelope-from ) id 1jCpAv-0000hP-0P; Fri, 13 Mar 2020 12:36:49 -0600 From: Logan Gunthorpe To: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Bjorn Helgaas Cc: Sebastian Andrzej Siewior , Logan Gunthorpe Date: Fri, 13 Mar 2020 12:36:08 -0600 Message-Id: <20200313183608.2646-1-logang@deltatee.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 172.16.1.31 X-SA-Exim-Rcpt-To: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, bhelgaas@google.com, bigeasy@linutronix.de, logang@deltatee.com X-SA-Exim-Mail-From: gunthorp@deltatee.com X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on ale.deltatee.com X-Spam-Level: X-Spam-Status: No, score=-8.7 required=5.0 tests=ALL_TRUSTED,BAYES_00, GREYLIST_ISWHITE,MYRULES_NO_TEXT,SURBL_BLOCKED,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.2 Subject: [PATCH] PCI/switchtec: Fix init_completion race condition with poll_wait() X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org The call to init_completion() in mrpc_queue_cmd() can theoretically race with the call to poll_wait() in switchtec_dev_poll(). poll() write() switchtec_dev_poll() switchtec_dev_write() poll_wait(&s->comp.wait); mrpc_queue_cmd() init_completion(&s->comp) init_waitqueue_head(&s->comp.wait) To my knowledge, no one has hit this bug, but we should fix it for correctness. Fix this by using reinit_completion() instead of init_completion() in mrpc_queue_cmd(). Fixes: 080b47def5e5 ("MicroSemi Switchtec management interface driver") Reported-by: Sebastian Andrzej Siewior Signed-off-by: Logan Gunthorpe Acked-by: Thomas Gleixner --- drivers/pci/switch/switchtec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c index a823b4b8ef8a..81dc7ac01381 100644 --- a/drivers/pci/switch/switchtec.c +++ b/drivers/pci/switch/switchtec.c @@ -175,7 +175,7 @@ static int mrpc_queue_cmd(struct switchtec_user *stuser) kref_get(&stuser->kref); stuser->read_len = sizeof(stuser->data); stuser_set_state(stuser, MRPC_QUEUED); - init_completion(&stuser->comp); + reinit_completion(&stuser->comp); list_add_tail(&stuser->list, &stdev->mrpc_queue); mrpc_cmd_submit(stdev);