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Subject[PATCH] hwmon: pmbus: protect read-modify-write with lock
Date
The operation done in the pmbus_update_fan() function is a
read-modify-write operation but it lacks any kind of lock protection
which may cause problems if run more than once simultaneously. This
patch uses an existing update_lock mutex to fix this problem.

Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
---
drivers/hwmon/pmbus/pmbus_core.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index ef7ee90ee785..94adbede7912 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -268,6 +268,7 @@ int pmbus_update_fan(struct i2c_client *client, int page, int id,
int rv;
u8 to;

+ mutex_lock(&data->update_lock);
from = pmbus_read_byte_data(client, page,
pmbus_fan_config_registers[id]);
if (from < 0)
@@ -278,11 +279,15 @@ int pmbus_update_fan(struct i2c_client *client, int page, int id,
rv = pmbus_write_byte_data(client, page,
pmbus_fan_config_registers[id], to);
if (rv < 0)
- return rv;
+ goto out;
}

- return _pmbus_write_word_data(client, page,
- pmbus_fan_command_registers[id], command);
+ rv = _pmbus_write_word_data(client, page,
+ pmbus_fan_command_registers[id], command);
+
+out:
+ mutex_lock(&data->update_lock);
+ return rv;
}
EXPORT_SYMBOL_GPL(pmbus_update_fan);

--
2.20.1
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