[PATCH v5 06/15] iio: adc: ad4134: Protect conventional device access from debug accesses

[Marcelo Schmitt]

Require debug access to acquire device synchronization locks before
allowing any transfer from the debug interface so to avoid disrupting
operations issued from usual (non-debug) interfaces.

Signed-off-by: Marcelo Schmitt <marcelo.schmitt@xxxxxxxxxx>
---
New patch in v5.

I'm not sure about this one and have no strong opinion about it.
Providing it according to suggestion from Nuno.
https://lore.kernel.org/linux-iio/179199692826.658576.4841754843069240356.b4-review@b4/
>From previous discussions I guess this patch might not be welcome.
https://lore.kernel.org/linux-iio/20250421142359.11fb483f@jic23-huawei/
In that case, completely fine with it being dropped.

 drivers/iio/adc/ad4134.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/iio/adc/ad4134.c b/drivers/iio/adc/ad4134.c
index dc4d801490db..42a1272c2894 100644
--- a/drivers/iio/adc/ad4134.c
+++ b/drivers/iio/adc/ad4134.c
@@ -302,6 +302,12 @@ static int ad4134_debugfs_reg_access(struct iio_dev *indio_dev,
 {
 	struct ad4134_state *st = iio_priv(indio_dev);
 
+	IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
+	if (IIO_DEV_ACQUIRE_FAILED(claim))
+		return -EBUSY;
+
+	guard(mutex)(&st->sync_lock);
+
 	if (readval)
 		return regmap_read(st->regmap, reg, readval);
 
-- 
2.53.0