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Sat, 23 May 2026 11:28:08 -0700 (PDT) Received: from i-use-arch-btw ([2600:1006:b017:e193:bca5:670c:e4c:71ed]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-586f25d708bsm6870334e0c.1.2026.05.23.11.28.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 23 May 2026 11:28:08 -0700 (PDT) From: Maxwell Doose To: jic23@kernel.org, m32285159@gmail.com Cc: David Lechner , =?UTF-8?q?Nuno=20S=C3=A1?= , Andy Shevchenko , linux-iio@vger.kernel.org (open list:IIO SUBSYSTEM AND DRIVERS), linux-kernel@vger.kernel.org (open list) Subject: [PATCH v4] iio: chemical: scd30: Replace manual locking with RAII locking Date: Sat, 23 May 2026 13:25:32 -0500 Message-ID: <20260523182531.10146-2-m32285159@gmail.com> X-Mailer: git-send-email 2.54.0 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" scd30_core.c currently uses manual mutex_lock() and mutex_unlock() calls. Replace them with the newer guard(mutex)() for cleaner RAII patterns and to improve maintainability. Add new helper function scd30_trigger_handler_helper_locked() containing the critical section for scd30_trigger_handler(). After moving scd30_trigger_handler()'s critical section into the new helper, tune up control logic to return ret early and not memcpy() if it's an error condition. In addition, small refactor to replace "?:" operator with regular if/else returns. Signed-off-by: Maxwell Doose --- v2: - Fix callback issue as noted by Jonathan v1. - Refactor critical section of scd30_trigger_handler() into helper called scd30_trigger_handler_helper_locked(). - Revert removal of goto in scd30_trigger_handler(). v3: - Tune up helper to return early on failure condition per Jonathan's suggestion. v4: - Forgot to commit changes listed in v3, now fixed. drivers/iio/chemical/scd30_core.c | 68 ++++++++++++++++++++----------- 1 file changed, 44 insertions(+), 24 deletions(-) diff --git a/drivers/iio/chemical/scd30_core.c b/drivers/iio/chemical/scd30= _core.c index a665fcb78806..8dbba9a7c426 100644 --- a/drivers/iio/chemical/scd30_core.c +++ b/drivers/iio/chemical/scd30_core.c @@ -368,11 +368,13 @@ static ssize_t calibration_auto_enable_show(struct de= vice *dev, struct device_at int ret; u16 val; =20 - mutex_lock(&state->lock); - ret =3D scd30_command_read(state, CMD_ASC, &val); - mutex_unlock(&state->lock); + guard(mutex)(&state->lock); =20 - return ret ?: sysfs_emit(buf, "%d\n", val); + ret =3D scd30_command_read(state, CMD_ASC, &val); + if (ret) + return ret; + + return sysfs_emit(buf, "%d\n", val); } =20 static ssize_t calibration_auto_enable_store(struct device *dev, struct de= vice_attribute *attr, @@ -387,11 +389,13 @@ static ssize_t calibration_auto_enable_store(struct d= evice *dev, struct device_a if (ret) return ret; =20 - mutex_lock(&state->lock); - ret =3D scd30_command_write(state, CMD_ASC, val); - mutex_unlock(&state->lock); + guard(mutex)(&state->lock); =20 - return ret ?: len; + ret =3D scd30_command_write(state, CMD_ASC, val); + if (ret) + return ret; + + return len; } =20 static ssize_t calibration_forced_value_show(struct device *dev, struct de= vice_attribute *attr, @@ -402,11 +406,13 @@ static ssize_t calibration_forced_value_show(struct d= evice *dev, struct device_a int ret; u16 val; =20 - mutex_lock(&state->lock); - ret =3D scd30_command_read(state, CMD_FRC, &val); - mutex_unlock(&state->lock); + guard(mutex)(&state->lock); =20 - return ret ?: sysfs_emit(buf, "%d\n", val); + ret =3D scd30_command_read(state, CMD_FRC, &val); + if (ret) + return ret; + + return sysfs_emit(buf, "%d\n", val); } =20 static ssize_t calibration_forced_value_store(struct device *dev, struct d= evice_attribute *attr, @@ -424,11 +430,13 @@ static ssize_t calibration_forced_value_store(struct = device *dev, struct device_ if (val < SCD30_FRC_MIN_PPM || val > SCD30_FRC_MAX_PPM) return -EINVAL; =20 - mutex_lock(&state->lock); - ret =3D scd30_command_write(state, CMD_FRC, val); - mutex_unlock(&state->lock); + guard(mutex)(&state->lock); =20 - return ret ?: len; + ret =3D scd30_command_write(state, CMD_FRC, val); + if (ret) + return ret; + + return len; } =20 static IIO_DEVICE_ATTR_RO(sampling_frequency_available, 0); @@ -579,24 +587,36 @@ static irqreturn_t scd30_irq_thread_handler(int irq, = void *priv) return IRQ_HANDLED; } =20 +/* Meant ONLY for scd30_trigger_handler() */ +static int scd30_trigger_handler_helper_locked(struct iio_dev *indio_dev, + int *scan_data, int arr_size) +{ + struct scd30_state *state =3D iio_priv(indio_dev); + int ret; + + guard(mutex)(&state->lock); + + if (!iio_trigger_using_own(indio_dev)) + ret =3D scd30_read_poll(state); + else + ret =3D scd30_read_meas(state); + if (ret) + return ret; + memcpy(scan_data, state->meas, arr_size); + return 0; +} + static irqreturn_t scd30_trigger_handler(int irq, void *p) { struct iio_poll_func *pf =3D p; struct iio_dev *indio_dev =3D pf->indio_dev; - struct scd30_state *state =3D iio_priv(indio_dev); struct { int data[SCD30_MEAS_COUNT]; aligned_s64 ts; } scan =3D { }; int ret; =20 - mutex_lock(&state->lock); - if (!iio_trigger_using_own(indio_dev)) - ret =3D scd30_read_poll(state); - else - ret =3D scd30_read_meas(state); - memcpy(scan.data, state->meas, sizeof(state->meas)); - mutex_unlock(&state->lock); + ret =3D scd30_trigger_handler_helper_locked(indio_dev, scan.data, sizeof(= scan.data)); if (ret) goto out; =20 --=20 2.54.0