[PATCH v4 2/2] iio: gyro: mpu3050-core: fix pm_runtime error handling

[Antoniu Miclaus]

The return value of pm_runtime_get_sync() is not checked, allowing
the driver to access hardware that may fail to resume. The device
usage count is also unconditionally incremented. Use
pm_runtime_resume_and_get() which propagates errors and avoids
incrementing the usage count on failure.

In preenable, add pm_runtime_put_autosuspend() on set_8khz_samplerate()
failure since postdisable does not run when preenable fails.

Fixes: 3904b28efb2c ("iio: gyro: Add driver for the MPU-3050 gyroscope")
Reviewed-by: Linus Walleij <linusw@xxxxxxxxxx>
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@xxxxxxxxxx>
---
Changes in v4:
- Reword commit message
- Simplify preenable by collapsing the trailing return statements

 drivers/iio/gyro/mpu3050-core.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/gyro/mpu3050-core.c b/drivers/iio/gyro/mpu3050-core.c
index ee2fcd20545d..317e7b217ec6 100644
--- a/drivers/iio/gyro/mpu3050-core.c
+++ b/drivers/iio/gyro/mpu3050-core.c
@@ -322,7 +322,9 @@ static int mpu3050_read_raw(struct iio_dev *indio_dev,
 		}
 	case IIO_CHAN_INFO_RAW:
 		/* Resume device */
-		pm_runtime_get_sync(mpu3050->dev);
+		ret = pm_runtime_resume_and_get(mpu3050->dev);
+		if (ret)
+			return ret;
 		mutex_lock(&mpu3050->lock);
 
 		ret = mpu3050_set_8khz_samplerate(mpu3050);
@@ -647,14 +649,20 @@ static irqreturn_t mpu3050_trigger_handler(int irq, void *p)
 static int mpu3050_buffer_preenable(struct iio_dev *indio_dev)
 {
 	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+	int ret;
 
-	pm_runtime_get_sync(mpu3050->dev);
+	ret = pm_runtime_resume_and_get(mpu3050->dev);
+	if (ret)
+		return ret;
 
 	/* Unless we have OUR trigger active, run at full speed */
-	if (!mpu3050->hw_irq_trigger)
-		return mpu3050_set_8khz_samplerate(mpu3050);
+	if (!mpu3050->hw_irq_trigger) {
+		ret = mpu3050_set_8khz_samplerate(mpu3050);
+		if (ret)
+			pm_runtime_put_autosuspend(mpu3050->dev);
+	}
 
-	return 0;
+	return ret;
 }
 
 static int mpu3050_buffer_postdisable(struct iio_dev *indio_dev)
-- 
2.43.0