On 23 January 2018 11:40:21 GMT, "Ardelean, Alexandru" <alexandru.Ardelean@xxxxxxxxxx> wrote:
>On Tue, 2018-01-23 at 02:32 +0530, Shreeya Patel wrote:
>> iio_dev->mlock is to be used only by the IIO core for protecting
>> device mode changes between INDIO_DIRECT and INDIO_BUFFER.
>>
>> This patch replaces the use of mlock with the already established
>> buf_lock mutex.
>>
>> Introducing 'unlocked' __ade7758_spi_write_reg_8 and
>> __ade7758_spi_read_reg_8 functions to be used by
>ade7758_write_samp_freq
>> and ade7758_read_samp_freq which avoids nested locks and maintains
>> atomicity between bus and device frequency changes.
>>
>
>hey,
>
>note: i took the liberty of re-adjusting the reply list ;
>initial scope seemed too wide ;
>added Barry Song, as he's listed as the author of the driver ;
>
>about the patch:
>overall looks good
>comments inline
>
>> Signed-off-by: Shreeya Patel <shreeya.patel23498@xxxxxxxxx>
>> ---
>> drivers/staging/iio/meter/ade7758.h | 2 +-
>> drivers/staging/iio/meter/ade7758_core.c | 49
>+++++++++++++++++++++++---------
>> 2 files changed, 37 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/staging/iio/meter/ade7758.h
>b/drivers/staging/iio/meter/ade7758.h
>> index 6ae78d8..2de81b5 100644
>> --- a/drivers/staging/iio/meter/ade7758.h
>> +++ b/drivers/staging/iio/meter/ade7758.h
>> @@ -111,7 +111,7 @@
>> * @trig: data ready trigger registered with iio
>> * @tx: transmit buffer
>> * @rx: receive buffer
>> - * @buf_lock: mutex to protect tx and rx
>> + * @buf_lock: mutex to protect tx, rx, read and write frequency
>> **/
>> struct ade7758_state {
>> struct spi_device *us;
>> diff --git a/drivers/staging/iio/meter/ade7758_core.c
>b/drivers/staging/iio/meter/ade7758_core.c
>> index 7b7ffe5..7f8f8c4 100644
>> --- a/drivers/staging/iio/meter/ade7758_core.c
>> +++ b/drivers/staging/iio/meter/ade7758_core.c
>> @@ -24,17 +24,26 @@
>> #include "meter.h"
>> #include "ade7758.h"
>>
>> -int ade7758_spi_write_reg_8(struct device *dev, u8 reg_address, u8
>val)
>> +/* Unlocked version of ade7758_spi_write_reg_8 function */
>
>you can probably remove this comment
>
>> +int __ade7758_spi_write_reg_8(struct device *dev, u8 reg_address, u8
>val)
>
>maybe make this static ;
>this function does not seem to be exported outside of this file
>
>> {
>> - int ret;
>> struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> struct ade7758_state *st = iio_priv(indio_dev);
>>
>> - mutex_lock(&st->buf_lock);
>> st->tx[0] = ADE7758_WRITE_REG(reg_address);
>> st->tx[1] = val;
>>
>> - ret = spi_write(st->us, st->tx, 2);
>> + return spi_write(st->us, st->tx, 2);
>> +}
>> +
>> +int ade7758_spi_write_reg_8(struct device *dev, u8 reg_address, u8
>val)
>> +{
>> + int ret;
>> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> + struct ade7758_state *st = iio_priv(indio_dev);
>> +
>> + mutex_lock(&st->buf_lock);
>> + ret = __ade7758_spi_write_reg_8(dev, reg_address, val);
>> mutex_unlock(&st->buf_lock);
>>
>> return ret;
>> @@ -91,7 +100,8 @@ static int ade7758_spi_write_reg_24(struct device
>*dev, u8 reg_address,
>> return ret;
>> }
>>
>> -int ade7758_spi_read_reg_8(struct device *dev, u8 reg_address, u8
>*val)
>> +/* Unlocked version of ade7758_spi_read_reg_16 function */
>you can probably remove this comment as well
>
>> +int __ade7758_spi_read_reg_8(struct device *dev, u8 reg_address, u8
>*val)
>
>make this static as well
>
>> {
>> struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> struct ade7758_state *st = iio_priv(indio_dev);
>> @@ -111,7 +121,6 @@ int ade7758_spi_read_reg_8(struct device *dev, u8
>reg_address, u8 *val)
>> },
>> };
>>
>> - mutex_lock(&st->buf_lock);
>> st->tx[0] = ADE7758_READ_REG(reg_address);
>> st->tx[1] = 0;
>>
>> @@ -124,7 +133,19 @@ int ade7758_spi_read_reg_8(struct device *dev,
>u8 reg_address, u8 *val)
>> *val = st->rx[0];
>>
>> error_ret:
>> + return ret;
>> +}
>> +
>> +int ade7758_spi_read_reg_8(struct device *dev, u8 reg_address, u8
>*val)
>> +{
>> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> + struct ade7758_state *st = iio_priv(indio_dev);
>> + int ret;
>> +
>> + mutex_lock(&st->buf_lock);
>> + ret = __ade7758_spi_read_reg_8(dev, reg_address, val);
>> mutex_unlock(&st->buf_lock);
>> +
>> return ret;
>> }
>>
>> @@ -470,7 +491,7 @@ static int ade7758_read_samp_freq(struct device
>*dev, int *val)
>> int ret;
>> u8 t;
>>
>> - ret = ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, &t);
>> + ret = __ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, &t);
>> if (ret)
>> return ret;
>>
>> @@ -503,14 +524,14 @@ static int ade7758_write_samp_freq(struct
>device *dev, int val)
>> goto out;
>> }
>>
>> - ret = ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, ®);
>> + ret = __ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, ®);
>> if (ret)
>> goto out;
>>
>> reg &= ~(5 << 3);
>> reg |= t << 5;
>>
>> - ret = ade7758_spi_write_reg_8(dev, ADE7758_WAVMODE, reg);
>> + ret = __ade7758_spi_write_reg_8(dev, ADE7758_WAVMODE, reg);
>>
>> out:
>> return ret;
>> @@ -523,12 +544,13 @@ static int ade7758_read_raw(struct iio_dev
>*indio_dev,
>> long mask)
>> {
>> int ret;
>> + struct ade7758_state *st = iio_priv(indio_dev);
>>
>> switch (mask) {
>> case IIO_CHAN_INFO_SAMP_FREQ:
>> - mutex_lock(&indio_dev->mlock);
>> + mutex_lock(&st->buf_lock);
>
>This may be ok.
>I did not seem to find a general consensus on which lock should be held
>here.
>Some drivers use buf_lock, some use the device's mlock.
>
>I guess someone more familiar with the IIO framework would be more
>suited to comment here.
Mlock should never be taken directly. We just didn't police it well in the past.
There are safe functions now to protect against state changes from poll to push modes in IIO.
Here we only need to protect the read buffer.
>
>> ret = ade7758_read_samp_freq(&indio_dev->dev, val);
>> - mutex_unlock(&indio_dev->mlock);
>> + mutex_unlock(&st->buf_lock);
>> return ret;
>> default:
>> return -EINVAL;
>> @@ -542,14 +564,15 @@ static int ade7758_write_raw(struct iio_dev
>*indio_dev,
>> int val, int val2, long mask)
>> {
>> int ret;
>> + struct ade7758_state *st = iio_priv(indio_dev);
>>
>> switch (mask) {
>> case IIO_CHAN_INFO_SAMP_FREQ:
>> if (val2)
>> return -EINVAL;
>> - mutex_lock(&indio_dev->mlock);
>> + mutex_lock(&st->buf_lock);
>
>same here about the lock
This one protects buffers and read modify write cycle. Buf_lock covers that.
>
>> ret = ade7758_write_samp_freq(&indio_dev->dev, val);
>> - mutex_unlock(&indio_dev->mlock);
>> + mutex_unlock(&st->buf_lock);
>> return ret;
>> default:
>> return -EINVAL;
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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