linux-kernel - [PATCH] iio: ad7292: Prevent regulator double disable

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Message-ID: <Yv9O+9sxU7gAv3vM@fedora>
Date:   Fri, 19 Aug 2022 11:51:07 +0300
From:   Matti Vaittinen <mazziesaccount@...il.com>
To:     Matti Vaittinen <mazziesaccount@...il.com>,
        Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
Cc:     Marcelo Schmitt <marcelo.schmitt1@...il.com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Jonathan Cameron <jic23@...nel.org>, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] iio: ad7292: Prevent regulator double disable

The ad7292 tries to add an devm_action for disabling a regulator at
device detach using devm_add_action_or_reset(). The
devm_add_action_or_reset() does call the release function should adding
action fail. The driver inspects the value returned by
devm_add_action_or_reset() and manually calls regulator_disable() if
adding the action has failed. This leads to double disable and messes
the enable count for regulator.

Do not manually call disable if devm_add_action_or_reset() fails.

Fixes: 506d2e317a0a ("iio: adc: Add driver support for AD7292")
Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>

---

The bug was found during browsing the code. I don't have the hardware to
test this so reviewing and testing is highly appreciated.
---
 drivers/iio/adc/ad7292.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/iio/adc/ad7292.c b/drivers/iio/adc/ad7292.c
index 92c68d467c50..a2f9fda25ff3 100644
--- a/drivers/iio/adc/ad7292.c
+++ b/drivers/iio/adc/ad7292.c
@@ -287,10 +287,8 @@ static int ad7292_probe(struct spi_device *spi)

 		ret = devm_add_action_or_reset(&spi->dev,
 					       ad7292_regulator_disable, st);
-		if (ret) {
-			regulator_disable(st->reg);
+		if (ret)
 			return ret;
-		}

 		ret = regulator_get_voltage(st->reg);
 		if (ret < 0)
-- 
2.37.1

-- 
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
Simon says - in Latin please.
~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
Thanks to Simon Glass for the translation =] 

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