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authorAlexandru Ardelean <alexandru.ardelean@analog.com>2020-07-06 14:02:59 +0300
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2020-09-21 20:54:18 +0300
commitc8bb10c50d60cf4bd083eb7f7956999942694c90 (patch)
tree62911c388a6de869ab6b715177f5f05ac4f0f384 /drivers/iio/dac
parentb004fe33034cc64f72c20923be71cf1e6c9a624c (diff)
downloadlinux-c8bb10c50d60cf4bd083eb7f7956999942694c90.tar.xz
iio: dac: ad5592r: localize locks only where needed in ad5592r_read_raw()
Since there was a recently discovered issue with these locks, it probably makes sense to cleanup the code a bit, to prevent it from being used as an example/reference. This change moves the lock only where it is explicitly needed to protect resources from potential concurrent accesses. It also reworks the switch statements to do direct returns vs caching the return value on a variable. Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com> Link: https://lore.kernel.org/r/20200706110259.23947-3-alexandru.ardelean@analog.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Diffstat (limited to 'drivers/iio/dac')
-rw-r--r--drivers/iio/dac/ad5592r-base.c30
1 files changed, 15 insertions, 15 deletions
diff --git a/drivers/iio/dac/ad5592r-base.c b/drivers/iio/dac/ad5592r-base.c
index 008f103c5ef2..63514e3c6c18 100644
--- a/drivers/iio/dac/ad5592r-base.c
+++ b/drivers/iio/dac/ad5592r-base.c
@@ -380,32 +380,32 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
switch (m) {
case IIO_CHAN_INFO_RAW:
- mutex_lock(&st->lock);
-
if (!chan->output) {
+ mutex_lock(&st->lock);
ret = st->ops->read_adc(st, chan->channel, &read_val);
+ mutex_unlock(&st->lock);
if (ret)
- goto unlock;
+ return ret;
if ((read_val >> 12 & 0x7) != (chan->channel & 0x7)) {
dev_err(st->dev, "Error while reading channel %u\n",
chan->channel);
- ret = -EIO;
- goto unlock;
+ return -EIO;
}
read_val &= GENMASK(11, 0);
} else {
+ mutex_lock(&st->lock);
read_val = st->cached_dac[chan->channel];
+ mutex_unlock(&st->lock);
}
dev_dbg(st->dev, "Channel %u read: 0x%04hX\n",
chan->channel, read_val);
*val = (int) read_val;
- ret = IIO_VAL_INT;
- break;
+ return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = ad5592r_get_vref(st);
@@ -425,11 +425,13 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
mult = !!(st->cached_gp_ctrl &
AD5592R_REG_CTRL_ADC_RANGE);
+ mutex_unlock(&st->lock);
+
*val *= ++mult;
*val2 = chan->scan_type.realbits;
- ret = IIO_VAL_FRACTIONAL_LOG2;
- break;
+
+ return IIO_VAL_FRACTIONAL_LOG2;
case IIO_CHAN_INFO_OFFSET:
ret = ad5592r_get_vref(st);
@@ -439,15 +441,13 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
*val = (-34365 * 25) / ret;
else
*val = (-75365 * 25) / ret;
- ret = IIO_VAL_INT;
- break;
+
+ mutex_unlock(&st->lock);
+
+ return IIO_VAL_INT;
default:
return -EINVAL;
}
-
-unlock:
- mutex_unlock(&st->lock);
- return ret;
}
static int ad5592r_write_raw_get_fmt(struct iio_dev *indio_dev,