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=-8.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 C0BC1C04AB5 for ; Mon, 3 Jun 2019 16:18:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8F77A24BAC for ; Mon, 3 Jun 2019 16:18:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QUaTBxs2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728313AbfFCQSG (ORCPT ); Mon, 3 Jun 2019 12:18:06 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:37786 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726722AbfFCQSG (ORCPT ); Mon, 3 Jun 2019 12:18:06 -0400 Received: by mail-pl1-f195.google.com with SMTP id bh12so1097716plb.4; Mon, 03 Jun 2019 09:18:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=p4sHeMSwuiO6XHZeDrH9mLgYjDqfs6hfLwvHwXhnh6Q=; b=QUaTBxs2hk4MFyRB4Y9D/HBIuusX7H88wACTIFBVB4OMXVQ208dODgIKwWAdDBjzfr mdr2i/4w0bbZWAWviw3/c+5aE6ApmJFp0KedwAbanFkdDPxDDuVLD6QqqVGpmlxRvhwk 5zYZ/cGNJjBxYORG/YRZThjBSfQ+POwHgmlUpifLmJ7SxyR5f2U9RTEzCi/CO8o2bXJM pIlsmwcZHWfidKdTX7VyUpRc8H8BRiDlp8EpC9nvR21pUr5t45JXWgC4n/ETFxtCaWuc mPY6A2rtL20IlOM543ULfCFQwQe3WEM5t9BU38B4RzEUxMLFPJs7f//aitDT14qdDElN wFMg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=p4sHeMSwuiO6XHZeDrH9mLgYjDqfs6hfLwvHwXhnh6Q=; b=lILSJ69HVJ0IcJlyVzTFHaPeVFTlf3AFfsoAsMqSXEC4Ur1RnuwWlWAlgo4r9ImGgy 7JAM6lYY3ycfBVvgO1bKh9XXgvbNz6Y441J8DF1E3Oy6Z+9NWOw2CXIpBv7w/mTYeHiK Q82a1criKaRnM79PSGEn9DzEIYohZmnaN4aul80IuLSrKKGjGjqxJmNP5eeSEi3MaTW5 QItRHMFRcm3YbzLKK9vDRLqWe4nj7LIfNntc/924gW3/kkrKxLCacOfBjZg2olaIK3Dt GOsXcmi+q1qtNmiMD0cqiiQ0NcqVrTWO648bxDeAC9Vr2Nq0RhIDblNUvTvQHM3IJz/S vuFw== X-Gm-Message-State: APjAAAVzeCs4BmuHnqn2UKoRaQimrGC4xrrZRBV6QUYB2nC08/qj+Sem cn/2VZW94kNIxjI0cE9/syw= X-Google-Smtp-Source: APXvYqzNkbi/w84kqvDZRwpwMcg/rqSTN6cdXAR0R4mIyZEAvW5LnyVvKq3tfJnau3koZq1L+U4OUA== X-Received: by 2002:a17:902:29e6:: with SMTP id h93mr29425315plb.297.1559578685438; Mon, 03 Jun 2019 09:18:05 -0700 (PDT) Received: from localhost ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id a1sm286255pfo.153.2019.06.03.09.18.03 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 03 Jun 2019 09:18:04 -0700 (PDT) Date: Mon, 3 Jun 2019 09:18:02 -0700 From: Guenter Roeck To: "Sverdlin, Alexander (Nokia - DE/Ulm)" Cc: "Adamski, Krzysztof (Nokia - PL/Wroclaw)" , Jean Delvare , "linux-hwmon@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] hwmon: pmbus: protect read-modify-write with lock Message-ID: <20190603161802.GA11107@roeck-us.net> References: <20190530064509.GA13789@localhost.localdomain> <5ecab585-7e74-ea9f-8d33-93ab024e1a14@nokia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5ecab585-7e74-ea9f-8d33-93ab024e1a14@nokia.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-hwmon-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-hwmon@vger.kernel.org On Mon, Jun 03, 2019 at 01:11:45PM +0000, Sverdlin, Alexander (Nokia - DE/Ulm) wrote: > Hi! > > On 30/05/2019 08:45, Adamski, Krzysztof (Nokia - PL/Wroclaw) wrote: > > The operation done in the pmbus_update_fan() function is a > > read-modify-write operation but it lacks any kind of lock protection > > which may cause problems if run more than once simultaneously. This > > patch uses an existing update_lock mutex to fix this problem. > > > > Signed-off-by: Krzysztof Adamski > > --- > > > > I'm resending this patch to proper recipients this time. Sorry if the > > previous submission confused anybody. > > > > drivers/hwmon/pmbus/pmbus_core.c | 11 ++++++++--- > > 1 file changed, 8 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c > > index ef7ee90ee785..94adbede7912 100644 > > --- a/drivers/hwmon/pmbus/pmbus_core.c > > +++ b/drivers/hwmon/pmbus/pmbus_core.c > > @@ -268,6 +268,7 @@ int pmbus_update_fan(struct i2c_client *client, int page, int id, > > int rv; > > u8 to; > > > > + mutex_lock(&data->update_lock); > > from = pmbus_read_byte_data(client, page, > > pmbus_fan_config_registers[id]); > > if (from < 0) > > @@ -278,11 +279,15 @@ int pmbus_update_fan(struct i2c_client *client, int page, int id, > > rv = pmbus_write_byte_data(client, page, > > pmbus_fan_config_registers[id], to); > > if (rv < 0) > > - return rv; > > + goto out; > > } > > > > - return _pmbus_write_word_data(client, page, > > - pmbus_fan_command_registers[id], command); > > + rv = _pmbus_write_word_data(client, page, > > + pmbus_fan_command_registers[id], command); > > + > > +out: > > + mutex_lock(&data->update_lock); > > This has to be mutex_unlock()... > Not only that - it is also recursive. Guenter