linux-kernel - [patch 2/8] rtc: mc146818: Reduce spinlock section in mc146818_set

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Message-Id: <20201206220541.709243630@linutronix.de>
Date:   Sun, 06 Dec 2020 22:46:15 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Miroslav Lichvar <mlichvar@...hat.com>,
        John Stultz <john.stultz@...aro.org>,
        Prarit Bhargava <prarit@...hat.com>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        linux-rtc@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>
Subject: [patch 2/8] rtc: mc146818: Reduce spinlock section in mc146818_set_time()

No need to hold the lock and disable interrupts for doing math.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 drivers/rtc/rtc-mc146818-lib.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/drivers/rtc/rtc-mc146818-lib.c
+++ b/drivers/rtc/rtc-mc146818-lib.c
@@ -135,7 +135,6 @@ int mc146818_set_time(struct rtc_time *t
 	if (yrs > 255)	/* They are unsigned */
 		return -EINVAL;
 
-	spin_lock_irqsave(&rtc_lock, flags);
 #ifdef CONFIG_MACH_DECSTATION
 	real_yrs = yrs;
 	leap_yr = ((!((yrs + 1900) % 4) && ((yrs + 1900) % 100)) ||
@@ -164,10 +163,8 @@ int mc146818_set_time(struct rtc_time *t
 	/* These limits and adjustments are independent of
 	 * whether the chip is in binary mode or not.
 	 */
-	if (yrs > 169) {
-		spin_unlock_irqrestore(&rtc_lock, flags);
+	if (yrs > 169)
 		return -EINVAL;
-	}
 
 	if (yrs >= 100)
 		yrs -= 100;
@@ -183,6 +180,7 @@ int mc146818_set_time(struct rtc_time *t
 		century = bin2bcd(century);
 	}
 
+	spin_lock_irqsave(&rtc_lock, flags);
 	save_control = CMOS_READ(RTC_CONTROL);
 	CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
 	save_freq_select = CMOS_READ(RTC_FREQ_SELECT);