Commit 54c5970d authored by Alexandre Belloni's avatar Alexandre Belloni
Browse files

rtc: rv3029: remove race condition when update STATUS 

There is no lock preventing concurrent access to the status register from
bth the rtc subsystem and the hwmon subsystem. Use regmap_update_bits to
ensure updating RV3029_STATUS is properly locked.

Link: https://lore.kernel.org/r/20191214221022.622482-5-alexandre.belloni@bootlin.com


Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent 609e97fe

drivers/rtc/rtc-rv3029c2.c

+6 −28
Original line number Diff line number Diff line
@@ -147,19 +147,6 @@ static int rv3029_get_sr(struct device *dev, u8 *buf) 
	return 0;

}



static int rv3029_set_sr(struct device *dev, u8 val)

{

	u8 buf[1];

	int sr;



	buf[0] = val;

	sr = rv3029_write_regs(dev, RV3029_STATUS, buf, 1);

	dev_dbg(dev, "status = 0x%.2x (%d)\n", buf[0], buf[0]);

	if (sr < 0)

		return -EIO;

	return 0;

}



static int rv3029_eeprom_busywait(struct device *dev)

{

	int i, ret;
@@ -205,9 +192,9 @@ static int rv3029_eeprom_enter(struct device *dev) 
		/* We clear the bits and retry once just in case

		 * we had a brown out in early startup.

		 */

		sr &= ~RV3029_STATUS_VLOW1;

		sr &= ~RV3029_STATUS_VLOW2;

		ret = rv3029_set_sr(dev, sr);

		ret = regmap_update_bits(rv3029->regmap, RV3029_STATUS,

					 RV3029_STATUS_VLOW1 |

					 RV3029_STATUS_VLOW2, 0);

		if (ret < 0)

			return ret;

		usleep_range(1000, 10000);
@@ -515,6 +502,7 @@ static int rv3029_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) 


static int rv3029_set_time(struct device *dev, struct rtc_time *tm)

{

	struct rv3029_data *rv3029 = dev_get_drvdata(dev);

	u8 regs[8];

	int ret;
@@ -539,19 +527,9 @@ static int rv3029_set_time(struct device *dev, struct rtc_time *tm) 
	if (ret < 0)

		return ret;



	ret = rv3029_get_sr(dev, regs);

	if (ret < 0) {

		dev_err(dev, "%s: reading SR failed\n", __func__);

		return ret;

	}

	/* clear PON bit */

	ret = rv3029_set_sr(dev, (regs[0] & ~RV3029_STATUS_PON));

	if (ret < 0) {

		dev_err(dev, "%s: reading SR failed\n", __func__);

		return ret;

	}



	return 0;

	return regmap_update_bits(rv3029->regmap, RV3029_STATUS,

				  RV3029_STATUS_PON, 0);

}



static const struct rv3029_trickle_tab_elem {