From 59f92868176f191eefde70d284bdfc1ed76a84bc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
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=UTF-8
Content-transfer-encoding: 8bit
Git-commit: 59f92868176f191eefde70d284bdfc1ed76a84bc
Patch-mainline: v5.16-rc5
References: git-fixes
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@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>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
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 16407664182c..6c67192946aa 100644
--- 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(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;
--
2.31.1