Re: [PATCH] iio: proximity: rfd77402: Fix completion race condition in IRQ mode

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 04 Mar 2026 22:14:32 +0800
Felix Gu <ustc.gu@gmail.com> wrote:

> In IRQ mode, the completion was being reinitialized after the
> measurement command had already been sent to the hardware. This
> created a race condition where the IRQ handler could call complete()
> before reinit_completion() was executed. Consequently,
> wait_for_completion_timeout() would fail to see the signal and wait
> until it timed out.
> 
> Move reinit_completion() to occur before the measurement command is
> triggered to ensure the synchronization primitive is ready to
> capture the interrupt.
> 
> Fixes: dc81be96a73a ("iio: proximity: rfd77402: Add interrupt handling support")
> Signed-off-by: Felix Gu <ustc.gu@gmail.com>

Looks good to me. Shrikant, you know this driver better than I do so if you
can take a look as well that would be great.

Thanks,

J
> ---
>  drivers/iio/proximity/rfd77402.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/proximity/rfd77402.c b/drivers/iio/proximity/rfd77402.c
> index 6afdbfca3e5a..81b8daf17a54 100644
> --- a/drivers/iio/proximity/rfd77402.c
> +++ b/drivers/iio/proximity/rfd77402.c
> @@ -173,10 +173,8 @@ static int rfd77402_wait_for_result(struct rfd77402_data *data)
>  	struct i2c_client *client = data->client;
>  	int val, ret;
>  
> -	if (data->irq_en) {
> -		reinit_completion(&data->completion);
> +	if (data->irq_en)
>  		return rfd77402_wait_for_irq(data);
> -	}
>  
>  	/*
>  	 * As per RFD77402 datasheet section '3.1.1 Single Measure', the
> @@ -204,6 +202,9 @@ static int rfd77402_measure(struct rfd77402_data *data)
>  	if (ret < 0)
>  		return ret;
>  
> +	if (data->irq_en)
> +		reinit_completion(&data->completion);
> +
>  	ret = i2c_smbus_write_byte_data(client, RFD77402_CMD_R,
>  					RFD77402_CMD_SINGLE |
>  					RFD77402_CMD_VALID);
> 
> ---
> base-commit: c025f6cf4209e1542ec2afebe49f42bbaf1a5c7b
> change-id: 20260304-77402-ec479de1b9f6
> 
> Best regards,