Re: [PATCH v4 1/4] iio: adc: ti-ads7950: switch to using guard() notation

[Jonathan Cameron]

On Mon, 30 Mar 2026 05:21:25 -0400
Bartosz Golaszewski <brgl@xxxxxxxxxx> wrote:

> On Mon, 30 Mar 2026 11:18:14 +0200, Dmitry Torokhov
> <dmitry.torokhov@xxxxxxxxx> said:
> > On March 30, 2026 2:15:42 AM PDT, Bartosz Golaszewski <brgl@xxxxxxxxxx> wrote:  
> >>On Mon, 30 Mar 2026 00:47:06 +0200, Dmitry Torokhov
> >><dmitry.torokhov@xxxxxxxxx> said:  
> >>> guard() notation allows early returns when encountering errors, making
> >>> control flow more obvious. Use it.
> >>>
> >>> Reviewed-by: David Lechner <dlechner@xxxxxxxxxxxx>
> >>> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> >>> ---
> >>>  drivers/iio/adc/ti-ads7950.c | 83 +++++++++++++++++---------------------------
> >>>  1 file changed, 31 insertions(+), 52 deletions(-)
> >>>
> >>> diff --git a/drivers/iio/adc/ti-ads7950.c b/drivers/iio/adc/ti-ads7950.c
> >>> index 028acd42741f..6e9ea9cc33bf 100644
> >>> --- a/drivers/iio/adc/ti-ads7950.c
> >>> +++ b/drivers/iio/adc/ti-ads7950.c
> >>> @@ -299,18 +299,19 @@ static irqreturn_t ti_ads7950_trigger_handler(int irq, void *p)
> >>>  	struct ti_ads7950_state *st = iio_priv(indio_dev);
> >>>  	int ret;
> >>>
> >>> -	mutex_lock(&st->slock);
> >>> -	ret = spi_sync(st->spi, &st->ring_msg);
> >>> -	if (ret < 0)
> >>> -		goto out;
> >>> -
> >>> -	iio_push_to_buffers_with_ts_unaligned(indio_dev, &st->rx_buf[2],
> >>> -					      sizeof(*st->rx_buf) *
> >>> -					      TI_ADS7950_MAX_CHAN,
> >>> -					      iio_get_time_ns(indio_dev));
> >>> -
> >>> -out:
> >>> -	mutex_unlock(&st->slock);
> >>> +	do {
> >>> +		guard(mutex)(&st->slock);  
> >>
> >>Am I missing something? Why isn't it just a:
> >>
> >>	scoped_guard(mutex, &st->slock) {
> >>		...
> >>	}  
> >
> > Maintainer's preference. It was a scoped guard in the first iteration.
> >  
> 
> Fair enough, though I don't really understand that. It looks less readable this
> way IMO.

The reasoning is the subtle nature of what a break means in scoped_guard().
Perhaps one day we'll get used to treating those as loops (which they are
under the hood).  The do {} while() pattern makes the loop visible.

Jonathan

> 
> Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
>