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Commit 7447f045 authored by Noralf Trønnes's avatar Noralf Trønnes Committed by Greg Kroah-Hartman
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iio: dln2-adc: Fix lockdep complaint 



commit 59f92868176f191eefde70d284bdfc1ed76a84bc upstream.

When reading the voltage:

$ cat /sys/bus/iio/devices/iio\:device0/in_voltage0_raw

Lockdep complains:

[  153.910616] ======================================================
[  153.916918] WARNING: possible circular locking dependency detected
[  153.923221] 5.14.0+ #5 Not tainted
[  153.926692] ------------------------------------------------------
[  153.932992] cat/717 is trying to acquire lock:
[  153.937525] c2585358 (&indio_dev->mlock){+.+.}-{3:3}, at: iio_device_claim_direct_mode+0x28/0x44
[  153.946541]
               but task is already holding lock:
[  153.952487] c2585860 (&dln2->mutex){+.+.}-{3:3}, at: dln2_adc_read_raw+0x94/0x2bc [dln2_adc]
[  153.961152]
               which lock already depends on the new lock.

Fix this by not calling into the iio core underneath the dln2->mutex lock.

Fixes: 7c0299e8 ("iio: adc: Add support for DLN2 ADC")
Cc: Jack Andersen <jackoalan@gmail.com>
Signed-off-by: default avatarNoralf Trønnes <noralf@tronnes.org>
Link: https://lore.kernel.org/r/20211018113731.25723-1-noralf@tronnes.org


Cc: <Stable@vger.kernel.org>
Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4c0fa7ed

drivers/iio/adc/dln2-adc.c

+7 −8
Original line number Diff line number Diff line
@@ -248,7 +248,6 @@ static int dln2_adc_set_chan_period(struct dln2_adc *dln2, 
static int dln2_adc_read(struct dln2_adc *dln2, unsigned int channel)

{

	int ret, i;

	struct iio_dev *indio_dev = platform_get_drvdata(dln2->pdev);

	u16 conflict;

	__le16 value;

	int olen = sizeof(value);
@@ -257,13 +256,9 @@ static int dln2_adc_read(struct dln2_adc *dln2, unsigned int channel) 
		.chan = channel,

	};



	ret = iio_device_claim_direct_mode(indio_dev);

	if (ret < 0)

		return ret;



	ret = dln2_adc_set_chan_enabled(dln2, channel, true);

	if (ret < 0)

		goto release_direct;

		return ret;



	ret = dln2_adc_set_port_enabled(dln2, true, &conflict);

	if (ret < 0) {
@@ -300,8 +295,6 @@ static int dln2_adc_read(struct dln2_adc *dln2, unsigned int channel) 
	dln2_adc_set_port_enabled(dln2, false, NULL);

disable_chan:

	dln2_adc_set_chan_enabled(dln2, channel, false);

release_direct:

	iio_device_release_direct_mode(indio_dev);



	return ret;

}
@@ -337,10 +330,16 @@ static int dln2_adc_read_raw(struct iio_dev *indio_dev, 


	switch (mask) {

	case IIO_CHAN_INFO_RAW:

		ret = iio_device_claim_direct_mode(indio_dev);

		if (ret < 0)

			return ret;



		mutex_lock(&dln2->mutex);

		ret = dln2_adc_read(dln2, chan->channel);

		mutex_unlock(&dln2->mutex);



		iio_device_release_direct_mode(indio_dev);



		if (ret < 0)

			return ret;