[PATCH] iio: accel: kxsd9: Fix runtime PM error handling and scoping

[Biren Pandya]

The kxsd9 driver uses pm_runtime_get_sync() in multiple places without
checking its return value, which can lead to silent failures. It also
relies on manual pm_runtime_put_autosuspend() calls in various return
paths, which is prone to memory leaks if a return path is missed.

Fix the runtime PM handling by using the new scoped guards and proper
error checking:
- In kxsd9_write_raw() and kxsd9_read_raw(), use the scoped
  PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND() macro to safely automate
  cleanup on function return, while maintaining the behavior of
  waking up a suspended device via pm_runtime_resume_and_get().
  This allows us to cleanly remove all manual puts and error gotos.
- In kxsd9_buffer_preenable(), replace pm_runtime_get_sync() with
  pm_runtime_resume_and_get() to safely check for errors and handle
  usage-counter unwinding on failure.
- In kxsd9_common_remove(), replace pm_runtime_get_sync() with
  pm_runtime_resume_and_get() and only invoke kxsd9_power_down()
  if the resume succeeds. This prevents unbalanced regulator disable
  warnings and bus timeouts if the device is already suspended.

Signed-off-by: Biren Pandya <birenpandya@xxxxxxxxx>
---
 drivers/iio/accel/kxsd9.c | 50 +++++++++++++++++++--------------------
 1 file changed, 24 insertions(+), 26 deletions(-)

diff --git a/drivers/iio/accel/kxsd9.c b/drivers/iio/accel/kxsd9.c
index 4717d80fc24a..f23d1660e6da 100644
--- a/drivers/iio/accel/kxsd9.c
+++ b/drivers/iio/accel/kxsd9.c
@@ -139,68 +139,63 @@ static int kxsd9_write_raw(struct iio_dev *indio_dev,
 			   int val2,
 			   long mask)
 {
-	int ret = -EINVAL;
 	struct kxsd9_state *st = iio_priv(indio_dev);
 
-	pm_runtime_get_sync(st->dev);
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->dev, pm);
+	if (PM_RUNTIME_ACQUIRE_ERR(&pm))
+		return PM_RUNTIME_ACQUIRE_ERR(&pm);
 
 	if (mask == IIO_CHAN_INFO_SCALE) {
 		/* Check no integer component */
 		if (val)
 			return -EINVAL;
-		ret = kxsd9_write_scale(indio_dev, val2);
+		return kxsd9_write_scale(indio_dev, val2);
 	}
 
-	pm_runtime_put_autosuspend(st->dev);
-
-	return ret;
+	return -EINVAL;
 }
 
 static int kxsd9_read_raw(struct iio_dev *indio_dev,
 			  struct iio_chan_spec const *chan,
 			  int *val, int *val2, long mask)
 {
-	int ret = -EINVAL;
 	struct kxsd9_state *st = iio_priv(indio_dev);
 	unsigned int regval;
 	__be16 raw_val;
 	u16 nval;
+	int ret;
 
-	pm_runtime_get_sync(st->dev);
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->dev, pm);
+	if (PM_RUNTIME_ACQUIRE_ERR(&pm))
+		return PM_RUNTIME_ACQUIRE_ERR(&pm);
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		ret = regmap_bulk_read(st->map, chan->address, &raw_val,
 				       sizeof(raw_val));
 		if (ret)
-			goto error_ret;
+			return ret;
 		nval = be16_to_cpu(raw_val);
 		/* Only 12 bits are valid */
 		nval >>= 4;
 		*val = nval;
-		ret = IIO_VAL_INT;
-		break;
+		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_OFFSET:
 		/* This has a bias of -2048 */
 		*val = KXSD9_ZERO_G_OFFSET;
-		ret = IIO_VAL_INT;
-		break;
+		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		ret = regmap_read(st->map,
 				  KXSD9_REG_CTRL_C,
 				  &regval);
 		if (ret < 0)
-			goto error_ret;
+			return ret;
 		*val = 0;
 		*val2 = kxsd9_micro_scales[regval & KXSD9_CTRL_C_FS_MASK];
-		ret = IIO_VAL_INT_PLUS_MICRO;
-		break;
+		return IIO_VAL_INT_PLUS_MICRO;
 	}
 
-error_ret:
-	pm_runtime_put_autosuspend(st->dev);
-
-	return ret;
+	return -EINVAL;
 };
 
 static irqreturn_t kxsd9_trigger_handler(int irq, void *p)
@@ -239,9 +234,7 @@ static int kxsd9_buffer_preenable(struct iio_dev *indio_dev)
 {
 	struct kxsd9_state *st = iio_priv(indio_dev);
 
-	pm_runtime_get_sync(st->dev);
-
-	return 0;
+	return pm_runtime_resume_and_get(st->dev);
 }
 
 static int kxsd9_buffer_postdisable(struct iio_dev *indio_dev)
@@ -476,13 +469,18 @@ void kxsd9_common_remove(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct kxsd9_state *st = iio_priv(indio_dev);
+	int ret;
 
 	iio_triggered_buffer_cleanup(indio_dev);
 	iio_device_unregister(indio_dev);
-	pm_runtime_get_sync(dev);
-	pm_runtime_put_noidle(dev);
+
+	ret = pm_runtime_resume_and_get(dev);
 	pm_runtime_disable(dev);
-	kxsd9_power_down(st);
+
+	if (ret >= 0) {
+		kxsd9_power_down(st);
+		pm_runtime_put_noidle(dev);
+	}
 }
 EXPORT_SYMBOL_NS(kxsd9_common_remove, "IIO_KXSD9");
 
-- 
2.50.1 (Apple Git-155)