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

[Jonathan Cameron]

On Mon, 9 Mar 2026 22:32:58 +0530
Shrikant <raskar.shree97@xxxxxxxxx> wrote:

> On Wed, Mar 4, 2026 at 7:44 PM Felix Gu <ustc.gu@xxxxxxxxx> 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@xxxxxxxxx>
> > ---
> >  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);
> > +  
> Looks good to me.
> Reviewed-by: Shrikant Raskar <raskar.shree97@xxxxxxxxx>
> 
Applied to the fixes-togreg branch of iio.git. Note I just sent a pull
request on that so will probably rebase after that (hopefully) gets
merged into char-misc-linus.

Thanks,

Jonathan
> Regards,
> Shrikant