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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C65DC433EF for ; Sat, 30 Oct 2021 21:48:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 756A860FC4 for ; Sat, 30 Oct 2021 21:48:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232145AbhJ3Vua (ORCPT ); Sat, 30 Oct 2021 17:50:30 -0400 Received: from mx-out.tlen.pl ([193.222.135.142]:45528 "EHLO mx-out.tlen.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232042AbhJ3VuT (ORCPT ); Sat, 30 Oct 2021 17:50:19 -0400 Received: (wp-smtpd smtp.tlen.pl 27089 invoked from network); 30 Oct 2021 23:47:44 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=o2.pl; s=1024a; t=1635630464; bh=6EV3+Db16M1TTmcxm0Ltf+cHXWaK6K5VL+dcc/n0F48=; h=From:To:Cc:Subject; b=nKPWUIuPkOCUlSBwb2L5EbGfTLpPQ6MOYEP0HvfakKWE1yEINnzqE6mNlYqn/qYJ1 zrh2TpT6oZfYrcnYoejH9FxRRLwLmwsZ41uB5zpryaR3npQBPJi0cdh0xXRPeS7b9h Qla3oeTO6r3Hxo9OuYCcO585bjjVBcEsi8Tb3q00= Received: from ablz112.neoplus.adsl.tpnet.pl (HELO localhost.localdomain) (mat.jonczyk@o2.pl@[83.7.219.112]) (envelope-sender ) by smtp.tlen.pl (WP-SMTPD) with SMTP for ; 30 Oct 2021 23:47:44 +0200 From: =?UTF-8?q?Mateusz=20Jo=C5=84czyk?= To: linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Mateusz=20Jo=C5=84czyk?= , Alessandro Zummo , Alexandre Belloni Subject: [DEBUG PATCH v3] rtc-cmos: cmos_read_alarm bug demonstration Date: Sat, 30 Oct 2021 23:46:36 +0200 Message-Id: <20211030214636.49602-9-mat.jonczyk@o2.pl> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211030214636.49602-1-mat.jonczyk@o2.pl> References: <20211030214636.49602-1-mat.jonczyk@o2.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-WP-MailID: 750861c663260497be442ce509100eed X-WP-AV: skaner antywirusowy Poczty o2 X-WP-SPAM: NO 0000000 [QYOk] Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Before my commit "rtc-cmos: avoid UIP when reading alarm time", applying this patch and reading the CMOS time like so: while true; do cat /sys/class/rtc/rtc0/time ; sleep 0.5; done produces errors in dmesg on my Intel Kaby Lake laptop. Signed-off-by: Mateusz Jończyk Cc: Alessandro Zummo Cc: Alexandre Belloni --- drivers/rtc/rtc-cmos.c | 61 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index b6d7dd3cf066..3de049930745 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -43,6 +43,9 @@ #include #endif +#include +#include + /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */ #include @@ -220,6 +223,8 @@ static inline void cmos_write_bank2(unsigned char val, unsigned char addr) /*----------------------------------------------------------------*/ +static void cmos_read_alarm_uip_debugging(struct device *dev); + static int cmos_read_time(struct device *dev, struct rtc_time *t) { /* @@ -230,6 +235,8 @@ static int cmos_read_time(struct device *dev, struct rtc_time *t) return -EIO; mc146818_get_time(t); + + cmos_read_alarm_uip_debugging(dev); return 0; } @@ -338,6 +345,60 @@ static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t) return 0; } +static void cmos_read_alarm_uip_debugging(struct device *dev) +{ + unsigned long flags; + unsigned char rtc_uip_baseline, rtc_uip; + struct rtc_wkalrm t_baseline, t; + ktime_t time_start, time_end; + int i; + + spin_lock_irqsave(&rtc_lock, flags); + rtc_uip_baseline = CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP; + spin_unlock_irqrestore(&rtc_lock, flags); + + cmos_read_alarm(dev, &t_baseline); + + time_start = ktime_get(); + + for (i = 0; i < 2000; i++) { + spin_lock_irqsave(&rtc_lock, flags); + rtc_uip = CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP; + spin_unlock_irqrestore(&rtc_lock, flags); + + cmos_read_alarm(dev, &t); + + if (t_baseline.time.tm_sec != t.time.tm_sec) { + dev_err(dev, + "Inconsistent alarm tm_sec value: %d != %d (RTC_UIP = %d; %d)\n", + t_baseline.time.tm_sec, + t.time.tm_sec, + rtc_uip_baseline, rtc_uip); + } + if (t_baseline.time.tm_min != t.time.tm_min) { + dev_err(dev, + "Inconsistent alarm tm_min value: %d != %d (RTC_UIP = %d; %d)\n", + t_baseline.time.tm_min, + t.time.tm_min, + rtc_uip_baseline, rtc_uip); + } + if (t_baseline.time.tm_hour != t.time.tm_hour) { + dev_err(dev, + "Inconsistent alarm tm_hour value: %d != %d (RTC_UIP = %d; %d)\n", + t_baseline.time.tm_hour, + t.time.tm_hour, + rtc_uip_baseline, rtc_uip); + } + + } + + time_end = ktime_get(); + + pr_info_ratelimited("%s: loop executed in %lld ns\n", + __func__, ktime_to_ns(ktime_sub(time_end, time_start))); +} + + static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control) { unsigned char rtc_intr; -- 2.25.1