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=-20.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 CFB20C07E95 for ; Sun, 4 Jul 2021 23:17:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA9386135D for ; Sun, 4 Jul 2021 23:17:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233212AbhGDXTH (ORCPT ); Sun, 4 Jul 2021 19:19:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:50600 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234298AbhGDXO7 (ORCPT ); Sun, 4 Jul 2021 19:14:59 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E4C6B6192E; Sun, 4 Jul 2021 23:12:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625440323; bh=JVLNcAVvJA766fz17y2DwfSvWm1nR3bQ+DMjcfM4Kns=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cuJnQ9bDzc4XqowRkIYKcvoByoXaZxDoVRUh0oGosjASQp/FqUTd70EKoL4yWNBWd mPIeq2IhhgZYhdfEFHGTsmbNqzRa/g/I0A0OTGrj7iD4umQTX1Vs4bkd/ypkBQKgVx uOQNZOKVomPTfDn1IrohhcTonkoNg4wvkHqEu2tOiopaZBffnRWx0VQFEm6GhqSoy1 tImBtRT4G66XRhPwpEwDoJKk58PuLaVTF4hj1J7rvfogWtuwG/S3rQTLGuTKmyGFtv Z8AD55o4IYwHeixL4hvsSNpJ+a3tpR8ewoqHJIVwKuNw0jzVm0rfzfVOTTHll2GvoG 7q2+M2cIITibA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Hans Verkuil , Mauro Carvalho Chehab , Sasha Levin , linux-media@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 06/20] media: cobalt: fix race condition in setting HPD Date: Sun, 4 Jul 2021 19:11:41 -0400 Message-Id: <20210704231155.1491795-6-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210704231155.1491795-1-sashal@kernel.org> References: <20210704231155.1491795-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Hans Verkuil [ Upstream commit 3d37ef41bed0854805ab9af22c422267510e1344 ] The cobalt_s_bit_sysctrl reads the old register value over PCI, then changes a bit and sets writes the new value to the register. This is used among other things for setting the HPD output pin. But if the HPD is changed for multiple inputs at the same time, then this causes a race condition where a stale value is read. Serialize this function with a mutex. Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Sasha Levin --- drivers/media/pci/cobalt/cobalt-driver.c | 1 + drivers/media/pci/cobalt/cobalt-driver.h | 7 ++++++- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/media/pci/cobalt/cobalt-driver.c b/drivers/media/pci/cobalt/cobalt-driver.c index 979634000597..17b717a1c7fa 100644 --- a/drivers/media/pci/cobalt/cobalt-driver.c +++ b/drivers/media/pci/cobalt/cobalt-driver.c @@ -689,6 +689,7 @@ static int cobalt_probe(struct pci_dev *pci_dev, return -ENOMEM; cobalt->pci_dev = pci_dev; cobalt->instance = i; + mutex_init(&cobalt->pci_lock); retval = v4l2_device_register(&pci_dev->dev, &cobalt->v4l2_dev); if (retval) { diff --git a/drivers/media/pci/cobalt/cobalt-driver.h b/drivers/media/pci/cobalt/cobalt-driver.h index ed00dc9d9399..8f9454d30b95 100644 --- a/drivers/media/pci/cobalt/cobalt-driver.h +++ b/drivers/media/pci/cobalt/cobalt-driver.h @@ -262,6 +262,8 @@ struct cobalt { int instance; struct pci_dev *pci_dev; struct v4l2_device v4l2_dev; + /* serialize PCI access in cobalt_s_bit_sysctrl() */ + struct mutex pci_lock; void __iomem *bar0, *bar1; @@ -333,10 +335,13 @@ static inline u32 cobalt_g_sysctrl(struct cobalt *cobalt) static inline void cobalt_s_bit_sysctrl(struct cobalt *cobalt, int bit, int val) { - u32 ctrl = cobalt_read_bar1(cobalt, COBALT_SYS_CTRL_BASE); + u32 ctrl; + mutex_lock(&cobalt->pci_lock); + ctrl = cobalt_read_bar1(cobalt, COBALT_SYS_CTRL_BASE); cobalt_write_bar1(cobalt, COBALT_SYS_CTRL_BASE, (ctrl & ~(1UL << bit)) | (val << bit)); + mutex_unlock(&cobalt->pci_lock); } static inline u32 cobalt_g_sysstat(struct cobalt *cobalt) -- 2.30.2