| Message ID | c95c9a77fcef36b2a052282146950f23bbc1ebdc.1680790580.git.william.gray@linaro.org (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | Migrate STX104 to the regmap API | expand |
On Thu, 6 Apr 2023 10:40:10 -0400 William Breathitt Gray <william.gray@linaro.org> wrote: > The priv->chan_out_states array and actual DAC value can become > mismatched if stx104_write_raw() is called concurrently. Prevent such a > race condition by utilizing a mutex. > > Fixes: 97a445dad37a ("iio: Add IIO support for the DAC on the Apex Embedded Systems STX104") > Signed-off-by: William Breathitt Gray <william.gray@linaro.org> Marked these first two patches for stable as probably worth a backport even if no one notices the affect of the race. I'll queue them for the next merge window though as we are fairly late in this cycle and I don't want to delay the 4 patches that follow a whole cycle. Thanks, Jonathan > --- > Changes in v5: none > > drivers/iio/addac/stx104.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/iio/addac/stx104.c b/drivers/iio/addac/stx104.c > index e45b70aa5bb7..4239aafe42fc 100644 > --- a/drivers/iio/addac/stx104.c > +++ b/drivers/iio/addac/stx104.c > @@ -15,6 +15,7 @@ > #include <linux/kernel.h> > #include <linux/module.h> > #include <linux/moduleparam.h> > +#include <linux/mutex.h> > #include <linux/spinlock.h> > #include <linux/types.h> > > @@ -69,10 +70,12 @@ struct stx104_reg { > > /** > * struct stx104_iio - IIO device private data structure > + * @lock: synchronization lock to prevent I/O race conditions > * @chan_out_states: channels' output states > * @reg: I/O address offset for the device registers > */ > struct stx104_iio { > + struct mutex lock; > unsigned int chan_out_states[STX104_NUM_OUT_CHAN]; > struct stx104_reg __iomem *reg; > }; > @@ -178,9 +181,12 @@ static int stx104_write_raw(struct iio_dev *indio_dev, > if ((unsigned int)val > 65535) > return -EINVAL; > > + mutex_lock(&priv->lock); > + > priv->chan_out_states[chan->channel] = val; > iowrite16(val, &priv->reg->dac[chan->channel]); > > + mutex_unlock(&priv->lock); > return 0; > } > return -EINVAL; > @@ -351,6 +357,8 @@ static int stx104_probe(struct device *dev, unsigned int id) > > indio_dev->name = dev_name(dev); > > + mutex_init(&priv->lock); > + > /* configure device for software trigger operation */ > iowrite8(0, &priv->reg->acr); >
diff --git a/drivers/iio/addac/stx104.c b/drivers/iio/addac/stx104.c index e45b70aa5bb7..4239aafe42fc 100644 --- a/drivers/iio/addac/stx104.c +++ b/drivers/iio/addac/stx104.c @@ -15,6 +15,7 @@ #include <linux/kernel.h> #include <linux/module.h> #include <linux/moduleparam.h> +#include <linux/mutex.h> #include <linux/spinlock.h> #include <linux/types.h> @@ -69,10 +70,12 @@ struct stx104_reg { /** * struct stx104_iio - IIO device private data structure + * @lock: synchronization lock to prevent I/O race conditions * @chan_out_states: channels' output states * @reg: I/O address offset for the device registers */ struct stx104_iio { + struct mutex lock; unsigned int chan_out_states[STX104_NUM_OUT_CHAN]; struct stx104_reg __iomem *reg; }; @@ -178,9 +181,12 @@ static int stx104_write_raw(struct iio_dev *indio_dev, if ((unsigned int)val > 65535) return -EINVAL; + mutex_lock(&priv->lock); + priv->chan_out_states[chan->channel] = val; iowrite16(val, &priv->reg->dac[chan->channel]); + mutex_unlock(&priv->lock); return 0; } return -EINVAL; @@ -351,6 +357,8 @@ static int stx104_probe(struct device *dev, unsigned int id) indio_dev->name = dev_name(dev); + mutex_init(&priv->lock); + /* configure device for software trigger operation */ iowrite8(0, &priv->reg->acr);
The priv->chan_out_states array and actual DAC value can become mismatched if stx104_write_raw() is called concurrently. Prevent such a race condition by utilizing a mutex. Fixes: 97a445dad37a ("iio: Add IIO support for the DAC on the Apex Embedded Systems STX104") Signed-off-by: William Breathitt Gray <william.gray@linaro.org> --- Changes in v5: none drivers/iio/addac/stx104.c | 8 ++++++++ 1 file changed, 8 insertions(+)