From patchwork Mon Jul 19 14:47:49 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "gregkh@linuxfoundation.org" X-Patchwork-Id: 481081 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=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, 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 20104C07E95 for ; Mon, 19 Jul 2021 15:34:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0DC636135D for ; Mon, 19 Jul 2021 15:34:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237617AbhGSOxZ (ORCPT ); Mon, 19 Jul 2021 10:53:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:43056 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237933AbhGSOtb (ORCPT ); Mon, 19 Jul 2021 10:49:31 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 989CF611F2; Mon, 19 Jul 2021 15:30:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626708610; bh=0uJ50+GR1GXb++JGu48gzrWZBY9aV7V3ZS3Fu0rd30c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yXFRpKvYuBUrCPGHYK0irTWTqsnIekPhVWJ+i6L5Bs2Hk6kwsgdGPXXRHHYz140o1 szBbfbB8XKNSVaw1z/J/zMhGepxPNm+dKmpTV5/D1UCOLZjOyfu01v6HnPSBQwKGd8 pMNH2p3uwfrkO9WDJThMY1yDKc9gLuZn3wLVzWsg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hans Verkuil , Mauro Carvalho Chehab , Sasha Levin Subject: [PATCH 4.19 058/421] media: cobalt: fix race condition in setting HPD Date: Mon, 19 Jul 2021 16:47:49 +0200 Message-Id: <20210719144948.215015817@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144946.310399455@linuxfoundation.org> References: <20210719144946.310399455@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@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 4885e833c052..f422558e6392 100644 --- a/drivers/media/pci/cobalt/cobalt-driver.c +++ b/drivers/media/pci/cobalt/cobalt-driver.c @@ -675,6 +675,7 @@ 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 429bee4ef79c..883093e5adea 100644 --- a/drivers/media/pci/cobalt/cobalt-driver.h +++ b/drivers/media/pci/cobalt/cobalt-driver.h @@ -250,6 +250,8 @@ 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; @@ -319,10 +321,13 @@ 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)