From 9be282312aba37785b47100f52c0d6a033d70a48 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Noralf=20Tr=C3=B8nnes?= Date: Mon, 18 Oct 2021 13:37:31 +0200 Subject: [PATCH] iio: dln2-adc: Fix lockdep complaint MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: 7c0299e879dd ("iio: adc: Add support for DLN2 ADC") Cc: Jack Andersen Signed-off-by: Noralf Trønnes Link: https://lore.kernel.org/r/20211018113731.25723-1-noralf@tronnes.org Cc: Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/adc/dln2-adc.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/iio/adc/dln2-adc.c b/drivers/iio/adc/dln2-adc.c index 2a299bbd6acf..d43af161f275 100644 --- a/drivers/iio/adc/dln2-adc.c +++ b/drivers/iio/adc/dln2-adc.c @@ -251,7 +251,6 @@ 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); @@ -260,13 +259,9 @@ 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) { @@ -303,8 +298,6 @@ 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; } @@ -340,10 +333,16 @@ 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; -- 2.20.1