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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A36D4C433EF for ; Tue, 22 Feb 2022 11:03:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=veZIlppOVdwpoRzrN2JpcSj9xvTJQVhIYJLs8SIfCNE=; b=Wi3FFho7qR8D3x 1I+9gdpKJ4MB5ijEZr+0lThfNE3nSV2bKZbyFUddmVTmKsAq+eYEmIQGD1JTTbs4UfxoC0VUSSq/N sy6I4KX9w2RIAk1L/y2YZOyAvqK0TJxInGH5Nf/x40Rs+UsjIkD7dOzlAt0CC+0/pbl/xVnWXsoWU eDrHI20a/EMvfg14lRVzx+TfedOWSIA2W0rAfdSi39gR9op8UXfVLut8aLU5yPZXyzbu45HCWrFX0 tzRSuzgWPMlBPAataOeBANTyqqU3u2RRa1Zwf8IS48c2sJcFzAU90kUI+4scT9/6eUioREIng1I5m CmV61AbdO2YI5ItcEveg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nMSvk-009HL1-Lv; Tue, 22 Feb 2022 11:02:06 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nMSsJ-009FpP-9H for linux-arm-kernel@lists.infradead.org; Tue, 22 Feb 2022 10:58:33 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7A1C4106F; Tue, 22 Feb 2022 02:58:28 -0800 (PST) Received: from donnerap.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C17833F70D; Tue, 22 Feb 2022 02:58:26 -0800 (PST) Date: Tue, 22 Feb 2022 10:58:23 +0000 From: Andre Przywara To: Alessandro Zummo , Alexandre Belloni Cc: Maxime Ripard , Chen-Yu Tsai , Jernej Skrabec , Rob Herring , Ondrej Jirman , Icenowy Zheng , Samuel Holland , linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org, linux-rtc@vger.kernel.org Subject: Re: [PATCH v10 03/18] rtc: sun6i: Fix time overflow handling Message-ID: <20220222105823.0cf9b008@donnerap.cambridge.arm.com> In-Reply-To: <20220211122643.1343315-4-andre.przywara@arm.com> References: <20220211122643.1343315-1-andre.przywara@arm.com> <20220211122643.1343315-4-andre.przywara@arm.com> Organization: ARM X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; aarch64-unknown-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220222_025831_506777_BBEB4EBC X-CRM114-Status: GOOD ( 27.66 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 11 Feb 2022 12:26:28 +0000 Andre Przywara wrote: Hi Alessandro, Alexandre, I was wondering if you would consider taking this (as a fix)? This (time_gap > U32_MAX) comparison looks flawed by design, and we should use time_t these days anyway. Also, do you have an opinion on the other RTC patches? The linear day patch (v10 04/18)[1] and the broken-down alarm registers (v10 05/18)[2] were on the list for a while now and are needed by other SoCs as well (R329[3] and the RISC-V D1). Cheers, Andre [1] https://lore.kernel.org/linux-arm-kernel/20220211122643.1343315-5-andre.przywara@arm.com/ [2] https://lore.kernel.org/linux-arm-kernel/20220211122643.1343315-6-andre.przywara@arm.com/ [3] https://lore.kernel.org/linux-arm-kernel/20210802062212.73220-3-icenowy@sipeed.com/ > Using "unsigned long" for UNIX timestamps is never a good idea, and > comparing the value of such a variable against U32_MAX does not do > anything useful on 32-bit systems. > > Use the proper time64_t type when dealing with timestamps, and avoid > cutting down the time range unnecessarily. This also fixes the flawed > check for the alarm time being too far into the future. > > The check for this condition is actually somewhat theoretical, as the > RTC counts till 2033 only anyways, and 2^32 seconds from now is not > before the year 2157 - at which point I hope nobody will be using this > hardware anymore. > > Signed-off-by: Andre Przywara > Reviewed-by: Jernej Skrabec > --- > drivers/rtc/rtc-sun6i.c | 14 +++++--------- > 1 file changed, 5 insertions(+), 9 deletions(-) > > diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c > index 35b34d14a1db..dc3ae851841c 100644 > --- a/drivers/rtc/rtc-sun6i.c > +++ b/drivers/rtc/rtc-sun6i.c > @@ -139,7 +139,7 @@ struct sun6i_rtc_dev { > const struct sun6i_rtc_clk_data *data; > void __iomem *base; > int irq; > - unsigned long alarm; > + time64_t alarm; > > struct clk_hw hw; > struct clk_hw *int_osc; > @@ -511,10 +511,8 @@ static int sun6i_rtc_setalarm(struct device *dev, > struct rtc_wkalrm *wkalrm) struct sun6i_rtc_dev *chip = > dev_get_drvdata(dev); struct rtc_time *alrm_tm = &wkalrm->time; > struct rtc_time tm_now; > - unsigned long time_now = 0; > - unsigned long time_set = 0; > - unsigned long time_gap = 0; > - int ret = 0; > + time64_t time_now, time_set; > + int ret; > > ret = sun6i_rtc_gettime(dev, &tm_now); > if (ret < 0) { > @@ -529,9 +527,7 @@ static int sun6i_rtc_setalarm(struct device *dev, > struct rtc_wkalrm *wkalrm) return -EINVAL; > } > > - time_gap = time_set - time_now; > - > - if (time_gap > U32_MAX) { > + if ((time_set - time_now) > U32_MAX) { > dev_err(dev, "Date too far in the future\n"); > return -EINVAL; > } > @@ -540,7 +536,7 @@ static int sun6i_rtc_setalarm(struct device *dev, > struct rtc_wkalrm *wkalrm) writel(0, chip->base + SUN6I_ALRM_COUNTER); > usleep_range(100, 300); > > - writel(time_gap, chip->base + SUN6I_ALRM_COUNTER); > + writel(time_set - time_now, chip->base + SUN6I_ALRM_COUNTER); > chip->alarm = time_set; > > sun6i_rtc_setaie(wkalrm->enabled, chip); _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel