The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x f063a28002e3350088b4577c5640882bf4ea17ea # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025051218-shield-neuron-a082@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From f063a28002e3350088b4577c5640882bf4ea17ea Mon Sep 17 00:00:00 2001 From: Luca Ceresoli luca.ceresoli@bootlin.com Date: Fri, 21 Mar 2025 19:10:00 +0100 Subject: [PATCH] iio: light: opt3001: fix deadlock due to concurrent flag access
The threaded IRQ function in this driver is reading the flag twice: once to lock a mutex and once to unlock it. Even though the code setting the flag is designed to prevent it, there are subtle cases where the flag could be true at the mutex_lock stage and false at the mutex_unlock stage. This results in the mutex not being unlocked, resulting in a deadlock.
Fix it by making the opt3001_irq() code generally more robust, reading the flag into a variable and using the variable value at both stages.
Fixes: 94a9b7b1809f ("iio: light: add support for TI's opt3001 light sensor") Cc: stable@vger.kernel.org Signed-off-by: Luca Ceresoli luca.ceresoli@bootlin.com Link: https://patch.msgid.link/20250321-opt3001-irq-fix-v1-1-6c520d851562@bootlin.... Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com
diff --git a/drivers/iio/light/opt3001.c b/drivers/iio/light/opt3001.c index 65b295877b41..393a3d2fbe1d 100644 --- a/drivers/iio/light/opt3001.c +++ b/drivers/iio/light/opt3001.c @@ -788,8 +788,9 @@ static irqreturn_t opt3001_irq(int irq, void *_iio) int ret; bool wake_result_ready_queue = false; enum iio_chan_type chan_type = opt->chip_info->chan_type; + bool ok_to_ignore_lock = opt->ok_to_ignore_lock;
- if (!opt->ok_to_ignore_lock) + if (!ok_to_ignore_lock) mutex_lock(&opt->lock);
ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION); @@ -826,7 +827,7 @@ static irqreturn_t opt3001_irq(int irq, void *_iio) }
out: - if (!opt->ok_to_ignore_lock) + if (!ok_to_ignore_lock) mutex_unlock(&opt->lock);
if (wake_result_ready_queue)