On Wed, 16 Sep 2020 12:25:35 +0300 Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> wrote: > From: Sergiu Cuciurean <sergiu.cuciurean@xxxxxxxxxx> > > As part of the general cleanup of indio_dev->mlock, this change replaces > it with a local lock on the device's state from potential concurrent write > accesses from userspace. The write operation requires an SPI write, then > toggling of a GPIO, so the lock aims to protect the sanity of the entire > sequence of operation. > > This is part of a bigger cleanup. > Link: https://lore.kernel.org/linux-iio/CA+U=Dsoo6YABe5ODLp+eFNPGFDjk5ZeQEceGkqjxXcVEhLWubw@xxxxxxxxxxxxxx/ > > Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@xxxxxxxxxx> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> Applied to the togreg branch of iio.git and pushed out as testing for the autobuilders to play with it. Thanks, Jonathan > --- > drivers/iio/dac/ti-dac7612.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/dac/ti-dac7612.c b/drivers/iio/dac/ti-dac7612.c > index 07c9f39d54f1..4c0f4b5e9ff4 100644 > --- a/drivers/iio/dac/ti-dac7612.c > +++ b/drivers/iio/dac/ti-dac7612.c > @@ -22,6 +22,14 @@ struct dac7612 { > struct gpio_desc *loaddacs; > uint16_t cache[2]; > > + /* > + * Lock to protect the state of the device from potential concurrent > + * write accesses from userspace. The write operation requires an > + * SPI write, then toggling of a GPIO, so the lock aims to protect > + * the sanity of the entire sequence of operation. > + */ > + struct mutex lock; > + > /* > * DMA (thus cache coherency maintenance) requires the > * transfer buffers to live in their own cache lines. > @@ -101,9 +109,9 @@ static int dac7612_write_raw(struct iio_dev *iio_dev, > if (val == priv->cache[chan->channel]) > return 0; > > - mutex_lock(&iio_dev->mlock); > + mutex_lock(&priv->lock); > ret = dac7612_cmd_single(priv, chan->channel, val); > - mutex_unlock(&iio_dev->mlock); > + mutex_unlock(&priv->lock); > > return ret; > } > @@ -145,6 +153,8 @@ static int dac7612_probe(struct spi_device *spi) > iio_dev->num_channels = ARRAY_SIZE(priv->cache); > iio_dev->name = spi_get_device_id(spi)->name; > > + mutex_init(&priv->lock); > + > for (i = 0; i < ARRAY_SIZE(priv->cache); i++) { > ret = dac7612_cmd_single(priv, i, 0); > if (ret)
