This is a note to let you know that I've just added the patch titled iio: dln2-adc: Fix lockdep complaint to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: iio-dln2-adc-fix-lockdep-complaint.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 59f92868176f191eefde70d284bdfc1ed76a84bc Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@xxxxxxxxxxx> Date: Mon, 18 Oct 2021 13:37:31 +0200 Subject: iio: dln2-adc: Fix lockdep complaint MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Noralf Trønnes <noralf@xxxxxxxxxxx> 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 <jackoalan@xxxxxxxxx> Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20211018113731.25723-1-noralf@xxxxxxxxxxx Cc: <Stable@xxxxxxxxxxxxxxx> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/iio/adc/dln2-adc.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) --- a/drivers/iio/adc/dln2-adc.c +++ b/drivers/iio/adc/dln2-adc.c @@ -248,7 +248,6 @@ static int dln2_adc_set_chan_period(stru 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 .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_ 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; Patches currently in stable-queue which might be from noralf@xxxxxxxxxxx are queue-5.15/iio-dln2-adc-fix-lockdep-complaint.patch