linux-kernel - Re: [PATCH v2] iio: imu: bmi160: add mutex

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Message-ID: <9c9333cb-bd6c-0f29-f35b-7592f457c746@redhat.com>
Date:   Wed, 20 Jan 2021 07:06:23 -0800
From:   Tom Rix <trix@...hat.com>
To:     Guoqing Chi <chi962464zy@....com>
Cc:     martin.blumenstingl@...glemail.com, linux-kernel@...r.kernel.org,
        chiguoqing@...ong.com, huyue2@...ong.com, zhangwen@...ong.com,
        linux-iio@...r.kernel.org
Subject: Re: [PATCH v2] iio: imu: bmi160: add mutex_lock for avoiding race


On 1/19/21 5:48 PM, Guoqing Chi wrote:
> On Tue, 19 Jan 2021 06:54:45 -0800
> Tom Rix <trix@...hat.com> wrote:
>
>> On 1/19/21 3:22 AM, Guoqing Chi wrote:
>>> From: chiguoqing <chi962464zy@....com>
>>>
>>> Adding mutex_lock, when read and write reg need to use this lock to
>>> avoid race.
>>>
>>> Signed-off-by: Guoqing Chi <chiguoqing@...ong.com>
>>> ---
>>> v2:Follow write function to fix read function.
>>> Adding mutex init in core probe function.
>>> Adding break in switch case at read and write function.
>>>
>>>  drivers/iio/imu/bmi160/bmi160.h      |  2 ++
>>>  drivers/iio/imu/bmi160/bmi160_core.c | 34
>>> +++++++++++++++++++--------- 2 files changed, 25 insertions(+), 11
>>> deletions(-)
>>>
>>> diff --git a/drivers/iio/imu/bmi160/bmi160.h
>>> b/drivers/iio/imu/bmi160/bmi160.h index 32c2ea2d7112..0c189a8b5b53
>>> 100644 --- a/drivers/iio/imu/bmi160/bmi160.h
>>> +++ b/drivers/iio/imu/bmi160/bmi160.h
>>> @@ -3,9 +3,11 @@
>>>  #define BMI160_H_
>>>  
>>>  #include <linux/iio/iio.h>
>>> +#include <linux/mutex.h>
>>>  #include <linux/regulator/consumer.h>
>>>  
>>>  struct bmi160_data {
>>> +	struct mutex lock;
>>>  	struct regmap *regmap;
>>>  	struct iio_trigger *trig;
>>>  	struct regulator_bulk_data supplies[2];
>>> diff --git a/drivers/iio/imu/bmi160/bmi160_core.c
>>> b/drivers/iio/imu/bmi160/bmi160_core.c index
>>> 290b5ef83f77..e303378f4841 100644 ---
>>> a/drivers/iio/imu/bmi160/bmi160_core.c +++
>>> b/drivers/iio/imu/bmi160/bmi160_core.c @@ -452,26 +452,32 @@ static
>>> int bmi160_read_raw(struct iio_dev *indio_dev, int ret;
>>>  	struct bmi160_data *data = iio_priv(indio_dev);
>>>  
>>> +	mutex_lock(&data->lock);
>>>  	switch (mask) {
>>>  	case IIO_CHAN_INFO_RAW:
>>>  		ret = bmi160_get_data(data, chan->type,
>>> chan->channel2, val);
>>> -		if (ret)
>>> -			return ret;
>>> -		return IIO_VAL_INT;
>>> +		if (!ret)
>>> +			ret = IIO_VAL_INT;
>>> +		break;
>>>  	case IIO_CHAN_INFO_SCALE:
>>>  		*val = 0;
>>>  		ret = bmi160_get_scale(data,
>>>  				       bmi160_to_sensor(chan->type),
>>> val2);
>>> -		return ret ? ret : IIO_VAL_INT_PLUS_MICRO;
>>> +		if (!ret)
>>> +			ret = IIO_VAL_INT_PLUS_MICRO;  
>> Looking better, another question..
>>
>> Why does the write() function return the results directly while the
>> read() function
>>
>> translates them to other values ?
>>
>> Tom
> It is original design in this driver. In order to
> differentiate raw to scale and SAMP_FREQ, while the scale and SAMP_FREQ
> are needless. I think log information can be added for this purpose,
> and return results directly.
> It is not change the return values for my modify.It's best to keep the
> original design.Is that all right?

Ok.

Reviewed-by: Tom Rix <trix@...hat.com>

> Guoqing Chi
>>> +		break;
>>>  	case IIO_CHAN_INFO_SAMP_FREQ:
>>>  		ret = bmi160_get_odr(data,
>>> bmi160_to_sensor(chan->type), val, val2);
>>> -		return ret ? ret : IIO_VAL_INT_PLUS_MICRO;
>>> +		if (!ret)
>>> +			ret = IIO_VAL_INT_PLUS_MICRO;
>>> +		break;
>>>  	default:
>>> -		return -EINVAL;
>>> +		ret = -EINVAL;
>>>  	}
>>> +	mutex_unlock(&data->lock);
>>>  
>>> -	return 0;
>>> +	return ret;
>>>  }
>>>  
>>>  static int bmi160_write_raw(struct iio_dev *indio_dev,
>>> @@ -479,19 +485,24 @@ static int bmi160_write_raw(struct iio_dev
>>> *indio_dev, int val, int val2, long mask)
>>>  {
>>>  	struct bmi160_data *data = iio_priv(indio_dev);
>>> +	int result;
>>>  
>>> +	mutex_lock(&data->lock);
>>>  	switch (mask) {
>>>  	case IIO_CHAN_INFO_SCALE:
>>> -		return bmi160_set_scale(data,
>>> +		result = bmi160_set_scale(data,
>>>  					bmi160_to_sensor(chan->type),
>>> val2);
>>> +		break;
>>>  	case IIO_CHAN_INFO_SAMP_FREQ:
>>> -		return bmi160_set_odr(data,
>>> bmi160_to_sensor(chan->type),
>>> +		result = bmi160_set_odr(data,
>>> bmi160_to_sensor(chan->type), val, val2);
>>> +		break;
>>>  	default:
>>> -		return -EINVAL;
>>> +		result = -EINVAL;
>>>  	}
>>> +	mutex_unlock(&data->lock);
>>>  
>>> -	return 0;
>>> +	return result;
>>>  }
>>>  
>>>  static
>>> @@ -838,6 +849,7 @@ int bmi160_core_probe(struct device *dev,
>>> struct regmap *regmap, return -ENOMEM;
>>>  
>>>  	data = iio_priv(indio_dev);
>>> +	mutex_init(&data->lock);
>>>  	dev_set_drvdata(dev, indio_dev);
>>>  	data->regmap = regmap;
>>>