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iio: dln2-adc: Fix lockdep complaint

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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: 7c0299e879 ("iio: adc: Add support for DLN2 ADC")
Cc: Jack Andersen <jackoalan@gmail.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://lore.kernel.org/r/20211018113731.25723-1-noralf@tronnes.org
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Noralf Trønnes 2021-10-18 13:37:31 +02:00 committed by Jonathan Cameron
parent f711f28e71
commit 59f9286817
1 changed files with 7 additions and 8 deletions
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15
drivers/iio/adc/dln2-adc.c
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@ -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 @@ disable_port:
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;