From patchwork Tue Sep 15 14:12:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 263863 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=-12.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,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 1DF56C433E2 for ; Wed, 16 Sep 2020 00:04:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF94A2078D for ; Wed, 16 Sep 2020 00:04:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600214669; bh=TelFs5DRtu/ns8dH0C70STQs/zQzZTtdnUp8n6R4ye8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jqTMfyLBpfvJ8EL7Khm1ofne04bDmb4w1/8aoDsQ1SyMEFGHScifKOk/Q9gL+FKct PdQ/jkrQ/x/diJupQxyXmvRXKn6Drl3GBsZTliXHSelrCpX1eyXw9mp9BytrNGRm3B utgAq3XDKpgqk5p4McTUMmI3kP9umtIzc+6hvE6A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727175AbgIPAEV (ORCPT ); Tue, 15 Sep 2020 20:04:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:41426 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726980AbgIOO3B (ORCPT ); Tue, 15 Sep 2020 10:29:01 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8AF18229C9; Tue, 15 Sep 2020 14:21:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600179674; bh=TelFs5DRtu/ns8dH0C70STQs/zQzZTtdnUp8n6R4ye8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H0OsF7PsXH6tfCp2e1W+rY45MWbtMhpoiH9V6Td2XIRZCWIqXddLRX+MGRsHE609C 3VnVpf4FVP70cf5ztx8V4Ot8HxcitfQsFrYVwlxKUmOikYotczp+36v1Y1JoCTUNdP hgbnaYV32qnEfCS9nEMnql7HWRBbzh2JhywyWU/8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Angelo Compagnucci , Stable@vger.kernel.org, Jonathan Cameron Subject: [PATCH 5.4 074/132] iio: adc: mcp3422: fix locking scope Date: Tue, 15 Sep 2020 16:12:56 +0200 Message-Id: <20200915140647.812623816@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200915140644.037604909@linuxfoundation.org> References: <20200915140644.037604909@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Angelo Compagnucci commit 3f1093d83d7164e4705e4232ccf76da54adfda85 upstream. Locking should be held for the entire reading sequence involving setting the channel, waiting for the channel switch and reading from the channel. If not, reading from a channel can result mixing with the reading from another channel. Fixes: 07914c84ba30 ("iio: adc: Add driver for Microchip MCP3422/3/4 high resolution ADC") Signed-off-by: Angelo Compagnucci Link: https://lore.kernel.org/r/20200819075525.1395248-1-angelo.compagnucci@gmail.com Cc: Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/adc/mcp3422.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) --- a/drivers/iio/adc/mcp3422.c +++ b/drivers/iio/adc/mcp3422.c @@ -95,16 +95,12 @@ static int mcp3422_update_config(struct { int ret; - mutex_lock(&adc->lock); - ret = i2c_master_send(adc->i2c, &newconfig, 1); if (ret > 0) { adc->config = newconfig; ret = 0; } - mutex_unlock(&adc->lock); - return ret; } @@ -137,6 +133,8 @@ static int mcp3422_read_channel(struct m u8 config; u8 req_channel = channel->channel; + mutex_lock(&adc->lock); + if (req_channel != MCP3422_CHANNEL(adc->config)) { config = adc->config; config &= ~MCP3422_CHANNEL_MASK; @@ -151,7 +149,11 @@ static int mcp3422_read_channel(struct m msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]); } - return mcp3422_read(adc, value, &config); + ret = mcp3422_read(adc, value, &config); + + mutex_unlock(&adc->lock); + + return ret; } static int mcp3422_read_raw(struct iio_dev *iio,