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Thu, 04 Dec 2025 09:07:45 -0800 (PST) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Thu, 04 Dec 2025 12:07:43 -0500 Message-Id: Cc: =?utf-8?q?Nuno_S=C3=A1?= , "Andy Shevchenko" , "Guenter Roeck" , "Jonathan Cameron" , , , Subject: Re: [PATCH RFC 5/6] iio: health: max30102: Use cleanup.h for IIO locks From: "Kurt Borja" To: "David Lechner" , "Kurt Borja" , "Andy Shevchenko" , "Lars-Peter Clausen" , "Michael Hennerich" , "Jonathan Cameron" , "Benson Leung" , "Antoniu Miclaus" , "Gwendal Grignou" , "Shrikant Raskar" , "Per-Daniel Olsson" X-Mailer: aerc 0.21.0-0-g5549850facc2 References: <20251203-lock-impr-v1-0-b4a1fd639423@gmail.com> <20251203-lock-impr-v1-5-b4a1fd639423@gmail.com> In-Reply-To: On Wed Dec 3, 2025 at 4:52 PM -05, David Lechner wrote: > On 12/3/25 1:18 PM, Kurt Borja wrote: >> Simplify and drop "hacky" busy-waiting code in max30102_read_raw() by >> using scoped_guard(). >>=20 >> Signed-off-by: Kurt Borja >> --- >> drivers/iio/health/max30102.c | 24 +++++++----------------- >> 1 file changed, 7 insertions(+), 17 deletions(-) >>=20 >> diff --git a/drivers/iio/health/max30102.c b/drivers/iio/health/max30102= .c >> index 678720102f2b..c642842cb5fb 100644 >> --- a/drivers/iio/health/max30102.c >> +++ b/drivers/iio/health/max30102.c >> @@ -24,6 +24,7 @@ >> #include >> #include >> #include >> +#include >> =20 >> #define MAX30102_DRV_NAME "max30102" >> #define MAX30102_PART_NUMBER 0x15 >> @@ -468,6 +469,7 @@ static int max30102_read_raw(struct iio_dev *indio_d= ev, >> { >> struct max30102_data *data =3D iio_priv(indio_dev); >> int ret =3D -EINVAL; >> + bool direct_en; >> =20 >> switch (mask) { >> case IIO_CHAN_INFO_RAW: >> @@ -475,25 +477,13 @@ static int max30102_read_raw(struct iio_dev *indio= _dev, >> * Temperature reading can only be acquired when not in >> * shutdown; leave shutdown briefly when buffer not running >> */ >> -any_mode_retry: >> - if (!iio_device_claim_buffer(indio_dev)) { >> - /* >> - * This one is a *bit* hacky. If we cannot claim buffer >> - * mode, then try direct mode so that we make sure >> - * things cannot concurrently change. And we just keep >> - * trying until we get one of the modes... >> - */ >> - if (!iio_device_claim_direct(indio_dev)) >> - goto any_mode_retry; >> + scoped_guard(iio_device_claim, indio_dev) { > > scoped_guard() is sketchy in switch statements because there is > a hidden for loop. If someone came along later and put a break; > inside of the scope, it would break out of the hidden for loop > rather than the apparent switch case! > > Besides that, it adds extra indent that we could avoid. > >> + direct_en =3D !iio_buffer_enabled(indio_dev); >> =20 >> - ret =3D max30102_get_temp(data, val, true); >> - iio_device_release_direct(indio_dev); >> - } else { >> - ret =3D max30102_get_temp(data, val, false); >> - iio_device_release_buffer(indio_dev); >> + ret =3D max30102_get_temp(data, val, direct_en); >> + if (ret) >> + return ret; >> } >> - if (ret) >> - return ret; >> =20 >> ret =3D IIO_VAL_INT; >> break; >>=20 > > I would write the whole function like this: > > static int max30102_read_raw(struct iio_dev *indio_dev, > struct iio_chan_spec const *chan, > int *val, int *val2, long mask) > { > struct max30102_data *data =3D iio_priv(indio_dev); > int ret; > > switch (mask) { > case IIO_CHAN_INFO_RAW: { > /* > * Temperature reading can only be acquired when not in > * shutdown; leave shutdown briefly when buffer not running > */ > guard(iio_device_claim)(indio_dev); AFAIK you can't guard() inside switch-case blocks. I don't know the exact reason, but it has to be scoped_guard(). > ret =3D max30102_get_temp(data, val, !iio_buffer_enabled(indio_dev)); > if (ret) > return ret; > > return IIO_VAL_INT; > } > case IIO_CHAN_INFO_SCALE: > *val =3D 1000; /* 62.5 */ > *val2 =3D 16; > return IIO_VAL_FRACTIONAL; > default: > return -EINVAL; > } > } > > Could also simplify things further by moving the call to iio_buffer_enabl= ed() > into max30102_get_temp(). I'll do it like this if this survives v2. --=20 ~ Kurt