[PATCH v6] Staging: iio: ade7758: Expand buf_lock to cover both buffer and state protection
Jonathan Cameron
jic23 at kernel.org
Sat Feb 10 15:28:38 UTC 2018
On Tue, 6 Feb 2018 22:31:57 +0530
Shreeya Patel <shreeya.patel23498 at gmail.com> 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' forms of read and write registers. The
> read/write frequency functions now require buf_lock to be held.
> That's not obvious so avoid this but moving the locking inside
> the functions where it is then clear that they are taking the
> unlocked forms of the register read/write.
>
> It isn't readily apparent that write frequency function requires
> the locks to be taken, so move it inside the function to where it
> is required to protect.
>
> Also, the read raw does not require iio_dev->mlock for
> reads. It can run concurrently as resource protection is handled
> by buf_lock in read register.
>
> Signed-off-by: Shreeya Patel <shreeya.patel23498 at gmail.com>
Applied to the togreg branch of iio.git.
Pushed out as testing for the autobuilders at 0day.org an
others to check we didn't get anything wrong.
I'll push out as a non rebasing tree next weekend as I'm offline
most of this week so won't be able to do it before then.
Jonathan
> ---
>
> Changes in v2
> -Add static keyword to newly introduced functions and remove some
> added comments which are not required.
>
> Changes in v3
> -Remove some useless mlocks and send it as another patch.
> Also make the necessary change in the current patch associated with
> the new patch with commit id 88eba33. Make commit message more
> appropriate.
>
> Changes in v4
> -Write frequency function do not require lock so move it inside
> the function to where it is required to protect.
>
> Changes in v5
> -Remove goto statement and make the code to return -EINVAL there
> itself.
>
> Changes in v6
> -Merge patch with commit id 88eba33 with this patch. Also make
> the changed function definition same as before.
>
> drivers/staging/iio/meter/ade7758.h | 2 +-
> drivers/staging/iio/meter/ade7758_core.c | 52 +++++++++++++++++++++++---------
> 2 files changed, 39 insertions(+), 15 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..4e0dbf5 100644
> --- a/drivers/staging/iio/meter/ade7758_core.c
> +++ b/drivers/staging/iio/meter/ade7758_core.c
> @@ -24,17 +24,25 @@
> #include "meter.h"
> #include "ade7758.h"
>
> -int ade7758_spi_write_reg_8(struct device *dev, u8 reg_address, u8 val)
> +static 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);
> 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 +99,7 @@ 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)
> +static 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);
> @@ -111,7 +119,6 @@ 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 +131,19 @@ 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;
> }
>
> @@ -484,6 +503,8 @@ static int ade7758_write_samp_freq(struct device *dev, int val)
> {
> int ret;
> u8 reg, t;
> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> + struct ade7758_state *st = iio_priv(indio_dev);
>
> switch (val) {
> case 26040:
> @@ -499,20 +520,23 @@ static int ade7758_write_samp_freq(struct device *dev, int val)
> t = 3;
> break;
> default:
> - ret = -EINVAL;
> - goto out;
> + return -EINVAL;
> }
>
> - ret = ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, ®);
> + mutex_lock(&st->buf_lock);
> +
> + 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:
> + mutex_unlock(&st->buf_lock);
> +
> return ret;
> }
>
> @@ -526,9 +550,9 @@ static int ade7758_read_raw(struct iio_dev *indio_dev,
>
> switch (mask) {
> case IIO_CHAN_INFO_SAMP_FREQ:
> - mutex_lock(&indio_dev->mlock);
> +
> ret = ade7758_read_samp_freq(&indio_dev->dev, val);
> - mutex_unlock(&indio_dev->mlock);
> +
> return ret;
> default:
> return -EINVAL;
> @@ -547,9 +571,9 @@ static int ade7758_write_raw(struct iio_dev *indio_dev,
> case IIO_CHAN_INFO_SAMP_FREQ:
> if (val2)
> return -EINVAL;
> - mutex_lock(&indio_dev->mlock);
> +
> ret = ade7758_write_samp_freq(&indio_dev->dev, val);
> - mutex_unlock(&indio_dev->mlock);
> +
> return ret;
> default:
> return -EINVAL;
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