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iio: light: opt3001: fix mutex unlock race 

When an end-of-conversion interrupt is received after performing a
single-shot reading of the light sensor, the driver was waking up the
result ready queue before checking opt->ok_to_ignore_lock to determine
if it should unlock the mutex. The problem occurred in the case where
the other thread woke up and changed the value of opt->ok_to_ignore_lock
to false prior to the interrupt thread performing its read of the
variable. In this case, the mutex would be unlocked twice.

Signed-off-by: David Frey <dpfrey@gmail.com>
Reviewed-by: Andreas Dannenberg <dannenberg@ti.com>
Fixes: 94a9b7b180 ("iio: light: add support for TI's opt3001 light sensor")
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
alistair/sunxi64-5.4-dsi
David Frey 2019-09-19 15:54:18 -07:00 committed by Jonathan Cameron
parent c62dd44901
commit 82f3015635
1 changed files with 5 additions and 1 deletions
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6
drivers/iio/light/opt3001.c
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@ -686,6 +686,7 @@ static irqreturn_t opt3001_irq(int irq, void *_iio)
struct iio_dev *iio = _iio;
struct opt3001 *opt = iio_priv(iio);
int ret;
bool wake_result_ready_queue = false;
if (!opt->ok_to_ignore_lock)
mutex_lock(&opt->lock);
@ -720,13 +721,16 @@ static irqreturn_t opt3001_irq(int irq, void *_iio)
}
opt->result = ret;
opt->result_ready = true;
wake_up(&opt->result_ready_queue);
wake_result_ready_queue = true;
}
out:
if (!opt->ok_to_ignore_lock)
mutex_unlock(&opt->lock);
if (wake_result_ready_queue)
wake_up(&opt->result_ready_queue);
return IRQ_HANDLED;
}