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=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 EE4B7C11F6E for ; Sun, 4 Jul 2021 23:13:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB2036141C for ; Sun, 4 Jul 2021 23:13:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233634AbhGDXQQ (ORCPT ); Sun, 4 Jul 2021 19:16:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:50832 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233510AbhGDXOa (ORCPT ); Sun, 4 Jul 2021 19:14:30 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BF2E46198F; Sun, 4 Jul 2021 23:09:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625440200; bh=QscHBCdwyz845ByNO9AmsX1v5TFqG9DVE99wooaq7oI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pbrdEEz4dDqMw0eStAvRtHmSNlNPndcKvleqUxT5lB4z0UZSjzBDj0q/bHPHBjQHh UAld1omJ5Em0XLXHN9V4r5uyozB5XJ55i4v0xZtYwqjw8uh5m0fL2ua6zuhHVLAsle 5spZcj8y0Zax/R8qpy3kdD9mUmsQPz8/0EfzV43APimNSwiWN2Jmwy51bNyIeDkkS8 BDkv1cE0DMCdiH8JJjCiwseelkceTT8v8bXFzmsyrZ1QPgYrsgvo5kXYOVmcyycgbJ iMJlJ74riDqOX0rb2uZpbwlEy/VqH49ECfMYMAaRZ8EVnoGBlTidylxl5PQaTXld0y ObyVJ/vUfBM0A== 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 5.4 17/50] media: cobalt: fix race condition in setting HPD Date: Sun, 4 Jul 2021 19:09:05 -0400 Message-Id: <20210704230938.1490742-17-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210704230938.1490742-1-sashal@kernel.org> References: <20210704230938.1490742-1-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-media@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 0695078ef812..1bd8bbe57a30 100644 --- a/drivers/media/pci/cobalt/cobalt-driver.c +++ b/drivers/media/pci/cobalt/cobalt-driver.c @@ -667,6 +667,7 @@ 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 bca68572b324..12c33e035904 100644 --- a/drivers/media/pci/cobalt/cobalt-driver.h +++ b/drivers/media/pci/cobalt/cobalt-driver.h @@ -251,6 +251,8 @@ 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; @@ -320,10 +322,13 @@ 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