From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CF3D6157E64; Mon, 29 Jan 2024 17:08:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706548120; cv=none; b=JiEDdaQYs9SSMPPjZ1L/oXcMPPLS0XcfTLXPdSRtUnbSlNyiO55HGLHc8MyK92N3PD25q3K37j2enVkIehpapunn1uIeDnbVy1u4DwcVLIsjlgvz+hTMvucFhNwKnjPPSs/IZ4PRRD7h7mN/e2YfaUZGjay4ocLF1AQzgE5At+E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706548120; c=relaxed/simple; bh=JMsluGD6U+Yo35/pHS9oZqGpHm62o0xxTm0FCPCqNTw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=SZPWW7hlG8hf7uFgNA6Q4zaOGS477dAABRWYsWXNesee8p0/cWVMvIcOtkA7FrO30guzUrfCTBh4sAnVE+o4gc6Z8J/yZcbNVy+qg6g8M6Jq9/XALQHZuS72/XKklG1lFQqH1DFACBLQ3ZwxRbLkLAj37ZmOqiVzvh974DlLngI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pUKAxPGJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="pUKAxPGJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97889C43399; Mon, 29 Jan 2024 17:08:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1706548120; bh=JMsluGD6U+Yo35/pHS9oZqGpHm62o0xxTm0FCPCqNTw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pUKAxPGJM3IQg4KUt1j3SPrBsyUiokEszG66n/LsVb15cf1hw1pNtYgooMub4LV1/ G1FlI21+g9i+g9j3uXeCy+aQv1Q79oPfiFlR0QOeowJZ3zlJtkLd1gpo0LkP4Vl3/Y JT2F4wNKl9SQ9TaTC1PellMuvreYmuFFphjjLqOI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mario Limonciello , =?UTF-8?q?Mateusz=20Jo=C5=84czyk?= , Alexandre Belloni Subject: [PATCH 6.7 112/346] rtc: Add support for configuring the UIP timeout for RTC reads Date: Mon, 29 Jan 2024 09:02:23 -0800 Message-ID: <20240129170019.687900740@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240129170016.356158639@linuxfoundation.org> References: <20240129170016.356158639@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mario Limonciello commit 120931db07b49252aba2073096b595482d71857c upstream. The UIP timeout is hardcoded to 10ms for all RTC reads, but in some contexts this might not be enough time. Add a timeout parameter to mc146818_get_time() and mc146818_get_time_callback(). If UIP timeout is configured by caller to be >=100 ms and a call takes this long, log a warning. Make all callers use 10ms to ensure no functional changes. Cc: # 6.1.y Fixes: ec5895c0f2d8 ("rtc: mc146818-lib: extract mc146818_avoid_UIP") Signed-off-by: Mario Limonciello Tested-by: Mateusz Jończyk Reviewed-by: Mateusz Jończyk Acked-by: Mateusz Jończyk Link: https://lore.kernel.org/r/20231128053653.101798-4-mario.limonciello@amd.com Signed-off-by: Alexandre Belloni Signed-off-by: Greg Kroah-Hartman --- arch/alpha/kernel/rtc.c | 2 +- arch/x86/kernel/hpet.c | 2 +- arch/x86/kernel/rtc.c | 2 +- drivers/base/power/trace.c | 2 +- drivers/rtc/rtc-cmos.c | 6 +++--- drivers/rtc/rtc-mc146818-lib.c | 37 +++++++++++++++++++++++++++++-------- include/linux/mc146818rtc.h | 3 ++- 7 files changed, 38 insertions(+), 16 deletions(-) --- a/arch/alpha/kernel/rtc.c +++ b/arch/alpha/kernel/rtc.c @@ -80,7 +80,7 @@ init_rtc_epoch(void) static int alpha_rtc_read_time(struct device *dev, struct rtc_time *tm) { - int ret = mc146818_get_time(tm); + int ret = mc146818_get_time(tm, 10); if (ret < 0) { dev_err_ratelimited(dev, "unable to read current time\n"); --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -1438,7 +1438,7 @@ irqreturn_t hpet_rtc_interrupt(int irq, memset(&curr_time, 0, sizeof(struct rtc_time)); if (hpet_rtc_flags & (RTC_UIE | RTC_AIE)) { - if (unlikely(mc146818_get_time(&curr_time) < 0)) { + if (unlikely(mc146818_get_time(&curr_time, 10) < 0)) { pr_err_ratelimited("unable to read current time from RTC\n"); return IRQ_HANDLED; } --- a/arch/x86/kernel/rtc.c +++ b/arch/x86/kernel/rtc.c @@ -67,7 +67,7 @@ void mach_get_cmos_time(struct timespec6 return; } - if (mc146818_get_time(&tm)) { + if (mc146818_get_time(&tm, 10)) { pr_err("Unable to read current time from RTC\n"); now->tv_sec = now->tv_nsec = 0; return; --- a/drivers/base/power/trace.c +++ b/drivers/base/power/trace.c @@ -120,7 +120,7 @@ static unsigned int read_magic_time(void struct rtc_time time; unsigned int val; - if (mc146818_get_time(&time) < 0) { + if (mc146818_get_time(&time, 10) < 0) { pr_err("Unable to read current time from RTC\n"); return 0; } --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -231,7 +231,7 @@ static int cmos_read_time(struct device if (!pm_trace_rtc_valid()) return -EIO; - ret = mc146818_get_time(t); + ret = mc146818_get_time(t, 10); if (ret < 0) { dev_err_ratelimited(dev, "unable to read current time\n"); return ret; @@ -307,7 +307,7 @@ static int cmos_read_alarm(struct device * * Use the mc146818_avoid_UIP() function to avoid this. */ - if (!mc146818_avoid_UIP(cmos_read_alarm_callback, &p)) + if (!mc146818_avoid_UIP(cmos_read_alarm_callback, 10, &p)) return -EIO; if (!(p.rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { @@ -556,7 +556,7 @@ static int cmos_set_alarm(struct device * * Use mc146818_avoid_UIP() to avoid this. */ - if (!mc146818_avoid_UIP(cmos_set_alarm_callback, &p)) + if (!mc146818_avoid_UIP(cmos_set_alarm_callback, 10, &p)) return -ETIMEDOUT; cmos->alarm_expires = rtc_tm_to_time64(&t->time); --- a/drivers/rtc/rtc-mc146818-lib.c +++ b/drivers/rtc/rtc-mc146818-lib.c @@ -8,26 +8,31 @@ #include #endif +#define UIP_RECHECK_DELAY 100 /* usec */ +#define UIP_RECHECK_DELAY_MS (USEC_PER_MSEC / UIP_RECHECK_DELAY) +#define UIP_RECHECK_LOOPS_MS(x) (x / UIP_RECHECK_DELAY_MS) + /* * Execute a function while the UIP (Update-in-progress) bit of the RTC is - * unset. + * unset. The timeout is configurable by the caller in ms. * * Warning: callback may be executed more then once. */ bool mc146818_avoid_UIP(void (*callback)(unsigned char seconds, void *param), + int timeout, void *param) { int i; unsigned long flags; unsigned char seconds; - for (i = 0; i < 100; i++) { + for (i = 0; UIP_RECHECK_LOOPS_MS(i) < timeout; i++) { spin_lock_irqsave(&rtc_lock, flags); /* * Check whether there is an update in progress during which the * readout is unspecified. The maximum update time is ~2ms. Poll - * every 100 usec for completion. + * for completion. * * Store the second value before checking UIP so a long lasting * NMI which happens to hit after the UIP check cannot make @@ -37,7 +42,7 @@ bool mc146818_avoid_UIP(void (*callback) if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP) { spin_unlock_irqrestore(&rtc_lock, flags); - udelay(100); + udelay(UIP_RECHECK_DELAY); continue; } @@ -56,7 +61,7 @@ bool mc146818_avoid_UIP(void (*callback) */ if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP) { spin_unlock_irqrestore(&rtc_lock, flags); - udelay(100); + udelay(UIP_RECHECK_DELAY); continue; } @@ -72,6 +77,10 @@ bool mc146818_avoid_UIP(void (*callback) } spin_unlock_irqrestore(&rtc_lock, flags); + if (UIP_RECHECK_LOOPS_MS(i) >= 100) + pr_warn("Reading current time from RTC took around %li ms\n", + UIP_RECHECK_LOOPS_MS(i)); + return true; } return false; @@ -84,7 +93,7 @@ EXPORT_SYMBOL_GPL(mc146818_avoid_UIP); */ bool mc146818_does_rtc_work(void) { - return mc146818_avoid_UIP(NULL, NULL); + return mc146818_avoid_UIP(NULL, 10, NULL); } EXPORT_SYMBOL_GPL(mc146818_does_rtc_work); @@ -130,13 +139,25 @@ static void mc146818_get_time_callback(u p->ctrl = CMOS_READ(RTC_CONTROL); } -int mc146818_get_time(struct rtc_time *time) +/** + * mc146818_get_time - Get the current time from the RTC + * @time: pointer to struct rtc_time to store the current time + * @timeout: timeout value in ms + * + * This function reads the current time from the RTC and stores it in the + * provided struct rtc_time. The timeout parameter specifies the maximum + * time to wait for the RTC to become ready. + * + * Return: 0 on success, -ETIMEDOUT if the RTC did not become ready within + * the specified timeout, or another error code if an error occurred. + */ +int mc146818_get_time(struct rtc_time *time, int timeout) { struct mc146818_get_time_callback_param p = { .time = time }; - if (!mc146818_avoid_UIP(mc146818_get_time_callback, &p)) { + if (!mc146818_avoid_UIP(mc146818_get_time_callback, timeout, &p)) { memset(time, 0, sizeof(*time)); return -ETIMEDOUT; } --- a/include/linux/mc146818rtc.h +++ b/include/linux/mc146818rtc.h @@ -126,10 +126,11 @@ struct cmos_rtc_board_info { #endif /* ARCH_RTC_LOCATION */ bool mc146818_does_rtc_work(void); -int mc146818_get_time(struct rtc_time *time); +int mc146818_get_time(struct rtc_time *time, int timeout); int mc146818_set_time(struct rtc_time *time); bool mc146818_avoid_UIP(void (*callback)(unsigned char seconds, void *param), + int timeout, void *param); #endif /* _MC146818RTC_H */