iio: adc: ti-ads7950: Fix improper use of mlock

Indio->mlock is used for protecting the different iio device modes.
It is currently not being used in this way. Replace the lock with
an internal lock specifically used for protecting the SPI transfer
buffer.

Signed-off-by: Justin Chen <justinpopo6@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ti-ads7950.c b/drivers/iio/adc/ti-ads7950.c
index 0ad63592cc3c91ddfe8deca1e7ecfde6bb3a2968..1e47bef72bb79dc856cd25203c5b13c7a7a2cc77 100644 (file)
--- a/drivers/iio/adc/ti-ads7950.c
+++ b/drivers/iio/adc/ti-ads7950.c
@@ -56,6 +56,9 @@ struct ti_ads7950_state {
        struct spi_message      ring_msg;
        struct spi_message      scan_single_msg;
 
+       /* Lock to protect the spi xfer buffers */
+       struct mutex            slock;
+
        struct regulator        *reg;
        unsigned int            vref_mv;
 
@@ -268,6 +271,7 @@ static irqreturn_t ti_ads7950_trigger_handler(int irq, void *p)
        struct ti_ads7950_state *st = iio_priv(indio_dev);
        int ret;
 
+       mutex_lock(&st->slock);
        ret = spi_sync(st->spi, &st->ring_msg);
        if (ret < 0)
                goto out;
@@ -276,6 +280,7 @@ static irqreturn_t ti_ads7950_trigger_handler(int irq, void *p)
                                           iio_get_time_ns(indio_dev));
 
 out:
+       mutex_unlock(&st->slock);
        iio_trigger_notify_done(indio_dev->trig);
 
        return IRQ_HANDLED;
@@ -286,7 +291,7 @@ static int ti_ads7950_scan_direct(struct iio_dev *indio_dev, unsigned int ch)
        struct ti_ads7950_state *st = iio_priv(indio_dev);
        int ret, cmd;
 
-       mutex_lock(&indio_dev->mlock);
+       mutex_lock(&st->slock);
 
        cmd = TI_ADS7950_CR_WRITE | TI_ADS7950_CR_CHAN(ch) | st->settings;
        st->single_tx = cmd;
@@ -298,7 +303,7 @@ static int ti_ads7950_scan_direct(struct iio_dev *indio_dev, unsigned int ch)
        ret = st->single_rx;
 
 out:
-       mutex_unlock(&indio_dev->mlock);
+       mutex_unlock(&st->slock);
 
        return ret;
 }
@@ -432,16 +437,19 @@ static int ti_ads7950_probe(struct spi_device *spi)
        if (ACPI_COMPANION(&spi->dev))
                st->vref_mv = TI_ADS7950_VA_MV_ACPI_DEFAULT;
 
+       mutex_init(&st->slock);
+
        st->reg = devm_regulator_get(&spi->dev, "vref");
        if (IS_ERR(st->reg)) {
                dev_err(&spi->dev, "Failed get get regulator \"vref\"\n");
-               return PTR_ERR(st->reg);
+               ret = PTR_ERR(st->reg);
+               goto error_destroy_mutex;
        }
 
        ret = regulator_enable(st->reg);
        if (ret) {
                dev_err(&spi->dev, "Failed to enable regulator \"vref\"\n");
-               return ret;
+               goto error_destroy_mutex;
        }
 
        ret = iio_triggered_buffer_setup(indio_dev, NULL,
@@ -463,6 +471,8 @@ error_cleanup_ring:
        iio_triggered_buffer_cleanup(indio_dev);
 error_disable_reg:
        regulator_disable(st->reg);
+error_destroy_mutex:
+       mutex_destroy(&st->slock);
 
        return ret;
 }
@@ -475,6 +485,7 @@ static int ti_ads7950_remove(struct spi_device *spi)
        iio_device_unregister(indio_dev);
        iio_triggered_buffer_cleanup(indio_dev);
        regulator_disable(st->reg);
+       mutex_destroy(&st->slock);
 
        return 0;
 }