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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 BD963ECE587 for ; Tue, 1 Oct 2019 19:53:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 949B920842 for ; Tue, 1 Oct 2019 19:53:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726010AbfJATxp (ORCPT ); Tue, 1 Oct 2019 15:53:45 -0400 Received: from relay2-d.mail.gandi.net ([217.70.183.194]:41235 "EHLO relay2-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725851AbfJATxp (ORCPT ); Tue, 1 Oct 2019 15:53:45 -0400 X-Originating-IP: 86.202.229.42 Received: from localhost (lfbn-lyo-1-146-42.w86-202.abo.wanadoo.fr [86.202.229.42]) (Authenticated sender: alexandre.belloni@bootlin.com) by relay2-d.mail.gandi.net (Postfix) with ESMTPSA id E4C6240002; Tue, 1 Oct 2019 19:53:42 +0000 (UTC) Date: Tue, 1 Oct 2019 21:53:42 +0200 From: Alexandre Belloni To: Nick Crews Cc: Alessandro Zummo , linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org, Pavel Machek , enric.balletbo@collabora.com, bleung@chromium.org, dlaurie@chromium.org, djkurtz@chromium.org, dtor@google.com Subject: Re: [PATCH v3] rtc: wilco-ec: Handle reading invalid times Message-ID: <20191001195342.GH4106@piout.net> References: <20190925203209.79941-1-ncrews@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190925203209.79941-1-ncrews@chromium.org> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org Hi Nick, On 25/09/2019 14:32:09-0600, Nick Crews wrote: > If the RTC HW returns an invalid time, the rtc_year_days() > call would crash. This patch adds error logging in this > situation, and removes the tm_yday and tm_wday calculations. > These fields should not be relied upon by userspace > according to man rtc, and thus we don't need to calculate > them. > > Signed-off-by: Nick Crews > --- > drivers/rtc/rtc-wilco-ec.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/drivers/rtc/rtc-wilco-ec.c b/drivers/rtc/rtc-wilco-ec.c > index 8ad4c4e6d557..53da355d996a 100644 > --- a/drivers/rtc/rtc-wilco-ec.c > +++ b/drivers/rtc/rtc-wilco-ec.c > @@ -110,10 +110,15 @@ static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm) > tm->tm_mday = rtc.day; > tm->tm_mon = rtc.month - 1; > tm->tm_year = rtc.year + (rtc.century * 100) - 1900; > - tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year); > - > - /* Don't compute day of week, we don't need it. */ > - tm->tm_wday = -1; > + /* Ignore other tm fields, man rtc says userspace shouldn't use them. */ > + > + if (rtc_valid_tm(tm)) { > + dev_err(dev, > + "Time from RTC is invalid: second=%u, minute=%u, hour=%u, day=%u, month=%u, year=%u, century=%u", > + rtc.second, rtc.minute, rtc.hour, rtc.day, rtc.month, > + rtc.year, rtc.century); Do you mind using %ptR? At this point you already filled the tm struct anyway and if you print century separately, you can infer tm_year. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com