[PATCH v2 1/2] pmbus: (core) mutex_lock write in pmbus_set_samples - Adamski, Krzysztof (Nokia

From: "Adamski, Krzysztof (Nokia - PL/Wroclaw)"  <krzysztof.adamski@nokia.com>
To: Guenter Roeck <linux@roeck-us.net>, Jean Delvare <jdelvare@suse.com>
Cc: "linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>,
	"Sverdlin,
	Alexander (Nokia - DE/Ulm)" <alexander.sverdlin@nokia.com>
Subject: [PATCH v2 1/2] pmbus: (core) mutex_lock write in pmbus_set_samples
Date: Wed, 29 May 2019 14:33:52 +0000	[thread overview]
Message-ID: <25c0f33fa281e8fb9781b71bda9e2f570113df85.1559140351.git.krzysztof.adamski@nokia.com> (raw)

update_lock is a mutex intended to protect write operations. It was not
taken, however, when _pmbus_write_word_data is called from
pmbus_set_samples() function which may cause problems especially when
some PMBUS_VIRT_* operation is implemented as a read-modify-write cycle.

This patch makes sure the lock is held during the operation.

Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
---
 drivers/hwmon/pmbus/pmbus_core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index ef7ee90ee785..62cd213cc260 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -1946,7 +1946,9 @@ static ssize_t pmbus_set_samples(struct device *dev,
 	if (kstrtol(buf, 0, &val) < 0)
 		return -EINVAL;
 
+	mutex_lock(&data->update_lock);
 	ret = _pmbus_write_word_data(client, reg->page, reg->attr->reg, val);
+	mutex_unlock(&data->update_lock);
 
 	return ret ? : count;
 }
-- 
2.20.1

