iio: adc: mcp3422: fix locking on error path

[ Upstream commit a139ffa40f0c24b753838b8ef3dcf6ad10eb7854 ]

Reading from the chip should be unlocked on error path else the lock
could never being released.

Fixes: 07914c84ba30 ("iio: adc: Add driver for Microchip MCP3422/3/4 high resolution ADC")
Fixes: 3f1093d83d71 ("iio: adc: mcp3422: fix locking scope")
Acked-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Angelo Compagnucci <angelo.compagnucci@gmail.com>
Link: https://lore.kernel.org/r/20200901093218.1500845-1-angelo.compagnucci@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iio/adc/mcp3422.c b/drivers/iio/adc/mcp3422.c
index 39c3a7e972c19f48b4c60d1b5bb46ccc72308002..6cc6666180eb5742ebd08664cbc20aeb2337eb08 100644 (file)
--- a/drivers/iio/adc/mcp3422.c
+++ b/drivers/iio/adc/mcp3422.c
@@ -146,8 +146,10 @@ static int mcp3422_read_channel(struct mcp3422 *adc,
                config &= ~MCP3422_PGA_MASK;
                config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
                ret = mcp3422_update_config(adc, config);
-               if (ret < 0)
+               if (ret < 0) {
+                       mutex_unlock(&adc->lock);
                        return ret;
+               }
                msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
        }