From: Noralf Trønnes noralf@tronnes.org
stable inclusion from stable-v5.10.85 commit 69ae78c1abe7a968743996f86d6581d278c16c85 bugzilla: 186032 https://gitee.com/openeuler/kernel/issues/I4QVI4
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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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@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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Chen Jun chenjun102@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- 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 0d53ef18e045..b9811e856124 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;