linux-kernel - [PATCH v2 7/9] rtc; pcf2123: fix possible alarm race condition

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Message-Id: <20190814151002.7324-7-alexandre.belloni@bootlin.com>
Date:   Wed, 14 Aug 2019 17:10:00 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     linux-rtc@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
Subject: [PATCH v2 7/9] rtc; pcf2123: fix possible alarm race condition

Clear the flag after disabling the alarm to ensure the alarm doesn't fire
between clearing the flag and disabling the alarm.

Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
---
 drivers/rtc/rtc-pcf2123.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/rtc/rtc-pcf2123.c b/drivers/rtc/rtc-pcf2123.c
index 175aa8779623..26f43b619b48 100644
--- a/drivers/rtc/rtc-pcf2123.c
+++ b/drivers/rtc/rtc-pcf2123.c
@@ -272,13 +272,13 @@ static int pcf2123_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
 
 	dev_dbg(dev, "%s: alm is %ptR\n", __func__, &alm->time);
 
-	/* Ensure alarm flag is clear */
-	ret = regmap_update_bits(pcf2123->map, PCF2123_REG_CTRL2, CTRL2_AF, 0);
+	/* Disable alarm interrupt */
+	ret = regmap_update_bits(pcf2123->map, PCF2123_REG_CTRL2, CTRL2_AIE, 0);
 	if (ret)
 		return ret;
 
-	/* Disable alarm interrupt */
-	ret = regmap_update_bits(pcf2123->map, PCF2123_REG_CTRL2, CTRL2_AIE, 0);
+	/* Ensure alarm flag is clear */
+	ret = regmap_update_bits(pcf2123->map, PCF2123_REG_CTRL2, CTRL2_AF, 0);
 	if (ret)
 		return ret;
 
-- 
2.21.0