| Message ID | 20210125015344.106-1-chi962464zy@163.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,resend] iio: imu: bmi160: add mutex_lock for avoiding race | expand |
On Sun, 31 Jan 2021 11:21:43 +0000 Jonathan Cameron <jic23@kernel.org> wrote: > On Mon, 25 Jan 2021 09:53:44 +0800 > Guoqing Chi <chi962464zy@163.com> wrote: > > > From: chiguoqing <chi962464zy@163.com> > > > > Adding mutex_lock, when read and write reg need to use this lock to > > avoid race. > > > > Signed-off-by: Guoqing Chi <chiguoqing@yulong.com> > > Reviewed-by: Tom Rix <trix@redhat.com> > > Hi. Looking at this again, I'm not entirely sure I understand what > the race is. Could you give any example? > > Individual regmap accesses have their own internal protections > against races. We don't have an read modify write cycles that > I can see here, so I don't think there are any races. > > On another note however, there is a regmap_bulk_read into > a variable on the stack which is a problem for spi. Unlike i2c > the spi patch in regmap for bulk_reads can be zero copy which > means that the variable on the stack can be dma'd into. That's > a potential issue for some systems in which you can end up wiping > out whatever else gets changed in the same cacheline. > > To fix that, the variable should be in it's own cacheline. Either > do that by using kmalloc etc to put it on the stack, or add a > suitable buffer to priv, marked ___cacheline_aligned. Though once > you do that you will need locks to protect it as you've done > here. > > Jonathan Hi Jonathan It's my mistake. The regmap_bulk_read func has their own lock. So maybe we can give up my patch. Thanks. > > > > > --- > > 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; > > + 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; > >
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; + 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;