[PATCH] iio: adc: meson-saradc: Variables could be uninitalized if regmap_read() fails

[Yizhuo]

Several functions in this file are trying to use regmap_read() to
initialize the specific variable, however, if regmap_read() fails,
the variable could be uninitialized but used directly, which is
potentially unsafe. The return value of regmap_read() should be
checked and handled.

Signed-off-by: Yizhuo <yzhai...@ucr.edu>
---
 drivers/iio/adc/meson_saradc.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
index 7b28d045d271..4b6c2983ef39 100644
--- a/drivers/iio/adc/meson_saradc.c
+++ b/drivers/iio/adc/meson_saradc.c
@@ -323,6 +323,7 @@ static int meson_sar_adc_wait_busy_clear(struct iio_dev 
*indio_dev)
 {
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int regval, timeout = 10000;
+       int ret;
 
        /*
         * NOTE: we need a small delay before reading the status, otherwise
@@ -331,7 +332,9 @@ static int meson_sar_adc_wait_busy_clear(struct iio_dev 
*indio_dev)
         */
        do {
                udelay(1);
-               regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
+               ret = regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
+               if (ret)
+                       return ret;
        } while (FIELD_GET(MESON_SAR_ADC_REG0_BUSY_MASK, regval) && timeout--);
 
        if (timeout < 0)
@@ -346,6 +349,7 @@ static int meson_sar_adc_read_raw_sample(struct iio_dev 
*indio_dev,
 {
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int regval, fifo_chan, fifo_val, count;
+       int ret;
 
        if(!wait_for_completion_timeout(&priv->done,
                                msecs_to_jiffies(MESON_SAR_ADC_TIMEOUT)))
@@ -358,7 +362,10 @@ static int meson_sar_adc_read_raw_sample(struct iio_dev 
*indio_dev,
                return -EINVAL;
        }
 
-       regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, &regval);
+       ret = regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, &regval);
+       if (ret)
+               return ret;
+
        fifo_chan = FIELD_GET(MESON_SAR_ADC_FIFO_RD_CHAN_ID_MASK, regval);
        if (fifo_chan != chan->address) {
                dev_err(&indio_dev->dev,
@@ -491,6 +498,7 @@ static int meson_sar_adc_lock(struct iio_dev *indio_dev)
 {
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int val, timeout = 10000;
+       int ret;
 
        mutex_lock(&indio_dev->mlock);
 
@@ -506,7 +514,10 @@ static int meson_sar_adc_lock(struct iio_dev *indio_dev)
                 */
                do {
                        udelay(1);
-                       regmap_read(priv->regmap, MESON_SAR_ADC_DELAY, &val);
+                       ret = regmap_read(priv->regmap,
+                                               MESON_SAR_ADC_DELAY, &val);
+                       if (ret)
+                               return ret;
                } while (val & MESON_SAR_ADC_DELAY_BL30_BUSY && timeout--);
 
                if (timeout < 0) {
@@ -771,7 +782,7 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
 {
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int regval, i, ret;
-
+       int ret;
        /*
         * make sure we start at CH7 input since the other muxes are only used
         * for internal calibration.
@@ -784,7 +795,10 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
                 * BL30 to make sure BL30 gets the values it expects when
                 * reading the temperature sensor.
                 */
-               regmap_read(priv->regmap, MESON_SAR_ADC_REG3, &regval);
+               ret = regmap_read(priv->regmap, MESON_SAR_ADC_REG3, &regval);
+               if (ret)
+                       return ret;
+
                if (regval & MESON_SAR_ADC_REG3_BL30_INITIALIZED)
                        return 0;
        }
@@ -1013,8 +1027,12 @@ static irqreturn_t meson_sar_adc_irq(int irq, void *data)
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        unsigned int cnt, threshold;
        u32 regval;
+       int ret;
+
+       ret = regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
+       if (ret)
+               return ret;
 
-       regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
        cnt = FIELD_GET(MESON_SAR_ADC_REG0_FIFO_COUNT_MASK, regval);
        threshold = FIELD_GET(MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, regval);
 
-- 
2.17.1