[PATCH 21/38] iio: sensors-core: st: Clean-up error handling in st_sensors_read_axis_data()

Jonathan Cameron
2013-09-14T16:58:56Z

On 09/10/13 13:49, Lee Jones wrote:
> Gets rid of those unnecessary gotos.

Unfortunately it introduced a bug whilst it is at it. Sometimes
those gotos are necessary and the 'right' way to do things.
>
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
> drivers/iio/common/st_sensors/st_sensors_core.c | 17 +++++++----------
> 1 file changed, 7 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/iio/common/st_sensors/st_sensors_core.c b/drivers/iio/common/st_sensors/st_sensors_core.c
> index 8c4c54c..148f0e5 100644
> --- a/drivers/iio/common/st_sensors/st_sensors_core.c
> +++ b/drivers/iio/common/st_sensors/st_sensors_core.c
> @@ -331,26 +331,23 @@ static int st_sensors_read_axis_data(struct iio_dev *indio_dev,
> unsigned int byte_for_channel = ch->scan_type.storagebits >> 3;
>
> outdata = kmalloc(byte_for_channel, GFP_KERNEL);
> - if (!outdata) {
> - err = -EINVAL;
> - goto st_sensors_read_axis_data_error;
> - }
> + if (!outdata)
> + return -ENOMEM;
I agree this change makes complete sense.
>
> err = sdata->tf->read_multiple_byte(&sdata->tb, sdata->dev,
> ch->address, byte_for_channel,
> outdata, sdata->multiread_bit);
> - if (err < 0)
> - goto st_sensors_free_memory;
> + if (err < 0) {
> + kfree(outdata);
> + return err;
> + }
I don't like this change as....
>
> if (byte_for_channel == 2)
> *data = (s16)get_unaligned_le16(outdata);
> else if (byte_for_channel == 3)
> *data = (s32)st_sensors_get_unaligned_le24(outdata);
>
> -st_sensors_free_memory:
> - kfree(outdata);
you now don't free out data in the case of no error. This is precisely the case
where a goto is the correct way to handle things as the free need to occur whether
or not the error occurs.

> -st_sensors_read_axis_data_error:
> - return err;
> + return 0;
> }
>
> int st_sensors_read_info_raw(struct iio_dev *indio_dev,
>