5.4-stable review patch. If anyone has any objections, please let me know.
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From: Luca Ceresoli luca.ceresoli@bootlin.com
[ Upstream commit f063a28002e3350088b4577c5640882bf4ea17ea ]
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 [ Adjust context ] Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iio/light/opt3001.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/iio/light/opt3001.c +++ b/drivers/iio/light/opt3001.c @@ -691,8 +691,9 @@ static irqreturn_t opt3001_irq(int irq, struct opt3001 *opt = iio_priv(iio); int ret; bool wake_result_ready_queue = false; + 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); @@ -729,7 +730,7 @@ static irqreturn_t opt3001_irq(int irq, }
out: - if (!opt->ok_to_ignore_lock) + if (!ok_to_ignore_lock) mutex_unlock(&opt->lock);
if (wake_result_ready_queue)