staging: iio: ad9832: clean-up regulator 'reg'

[ This patch generates a GCC warning as well... I have no idea how we
failed so badly. -dan ]

Hello Eva Rachel Retuya,

The patch 43a07e48af44: "staging: iio: ad9832: clean-up regulator 'reg'" from Nov 1, 2016, leads to the following static checker warning:

	drivers/staging/iio/frequency/ad9832.c:214 ad9832_probe()
	error: potentially dereferencing uninitialized 'st'.

drivers/staging/iio/frequency/ad9832.c
202 static int ad9832_probe(struct spi_device *spi) 203 {

   204          struct ad9832_platform_data *pdata = dev_get_platdata(&spi->dev);
   205          struct iio_dev *indio_dev;
   206          struct ad9832_state *st;
   207          int ret;
   208  
   209          if (!pdata) {
   210                  dev_dbg(&spi->dev, "no platform data?\n");
   211                  return -ENODEV;
   212          }
   213  
   214          st->avdd = devm_regulator_get(&spi->dev, "avdd");
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Oops.

215 if (IS_ERR(st->avdd))
216 return PTR_ERR(st->avdd);
217
218 ret = regulator_enable(st->avdd);
219 if (ret) {
220 dev_err(&spi->dev, "Failed to enable specified AVDD supply\n");
221 return ret;
222 }
223
224 st->dvdd = devm_regulator_get(&spi->dev, "dvdd");
225 if (IS_ERR(st->dvdd)) {
226 ret = PTR_ERR(st->dvdd);
227 goto error_disable_avdd;
228 }
229
230 ret = regulator_enable(st->dvdd);
231 if (ret) {
232 dev_err(&spi->dev, "Failed to enable specified DVDD supply\n");
233 goto error_disable_avdd;
234 }
235
236 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
237 if (!indio_dev) {
238 ret = -ENOMEM;
239 goto error_disable_dvdd;

   240          }
   241          spi_set_drvdata(spi, indio_dev);
   242          st = iio_priv(indio_dev);
                ^^^^^^^^^^^^^^^^^^^^^^^^

"st" isn't initialized until here.

   243          st->mclk = pdata->mclk;
   244          st->spi = spi;

regards,
dan carpenter

Thank you for bringing this up. A patch has already been sent to fix it:
https://git.kernel.org/cgit/linux/kernel/git/jic23/iio.git/commit/?h=testing&id=6826fdbd2e207f8107e65c5a372ac616e7af11b4

Eva