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Sun, 22 Mar 2026 12:07:18 -0700 (PDT) From: Emre Cecanpunar To: platform-driver-x86@vger.kernel.org Cc: hansg@kernel.org, ilpo.jarvinen@linux.intel.com, linux-kernel@vger.kernel.org, krishna.chomal108@gmail.com, Emre Cecanpunar Subject: [PATCH v2 5/5] platform/x86: hp-wmi: add locking for concurrent hwmon access Date: Sun, 22 Mar 2026 22:06:24 +0300 Message-ID: <20260322190624.35162-6-emreleno@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260322190624.35162-1-emreleno@gmail.com> References: <20260322190624.35162-1-emreleno@gmail.com> 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" hp_wmi_hwmon_priv.mode and .pwm are written by hp_wmi_hwmon_write() in sysfs context and read by hp_wmi_hwmon_keep_alive_handler() running in a workqueue. There is no synchronisation between them, so a concurrent sysfs write and keep-alive expiry can observe an inconsistent combination of mode and pwm (e.g. mode=3DMANUAL with an stale pwm value from the previous mode). Add a mutex to hp_wmi_hwmon_priv that protects mode and pwm. Acquire it in hp_wmi_hwmon_write() for the full write operation (field update plus hp_wmi_apply_fan_settings() call), and in hp_wmi_hwmon_keep_alive_handler() before calling hp_wmi_apply_fan_settings(). In hp_wmi_hwmon_read(), only the pwm_enable attribute reads priv->mode and requires the lock. Use scoped_guard() to hold the mutex only for the mode read, avoiding holding it across unrelated WMI hardware calls. Signed-off-by: Emre Cecanpunar --- drivers/platform/x86/hp/hp-wmi.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/platform/x86/hp/hp-wmi.c b/drivers/platform/x86/hp/hp-= wmi.c index af57cb0dbf9e..0947aaeabff3 100644 --- a/drivers/platform/x86/hp/hp-wmi.c +++ b/drivers/platform/x86/hp/hp-wmi.c @@ -434,6 +434,7 @@ enum pwm_modes { }; =20 struct hp_wmi_hwmon_priv { + struct mutex lock; /* protects mode, pwm */ u8 min_rpm; u8 max_rpm; int gpu_delta; @@ -2403,6 +2404,7 @@ static int hp_wmi_hwmon_read(struct device *dev, enum= hwmon_sensor_types type, { struct hp_wmi_hwmon_priv *priv; int rpm, ret; + u8 mode; =20 priv =3D dev_get_drvdata(dev); switch (type) { @@ -2426,11 +2428,13 @@ static int hp_wmi_hwmon_read(struct device *dev, en= um hwmon_sensor_types type, *val =3D rpm_to_pwm(rpm / 100, priv); return 0; } - switch (priv->mode) { + scoped_guard(mutex, &priv->lock) + mode =3D priv->mode; + switch (mode) { case PWM_MODE_MAX: case PWM_MODE_MANUAL: case PWM_MODE_AUTO: - *val =3D priv->mode; + *val =3D mode; return 0; default: /* shouldn't happen */ @@ -2448,6 +2452,7 @@ static int hp_wmi_hwmon_write(struct device *dev, enu= m hwmon_sensor_types type, int rpm; =20 priv =3D dev_get_drvdata(dev); + guard(mutex)(&priv->lock); switch (type) { case hwmon_pwm: if (attr =3D=3D hwmon_pwm_input) { @@ -2516,6 +2521,8 @@ static void hp_wmi_hwmon_keep_alive_handler(struct wo= rk_struct *work) =20 dwork =3D to_delayed_work(work); priv =3D container_of(dwork, struct hp_wmi_hwmon_priv, keep_alive_dwork); + + guard(mutex)(&priv->lock); /* * Re-apply the current hwmon context settings. * NOTE: hp_wmi_apply_fan_settings will handle the re-scheduling. @@ -2573,6 +2580,8 @@ static int hp_wmi_hwmon_init(void) if (!priv) return -ENOMEM; =20 + mutex_init(&priv->lock); + ret =3D hp_wmi_setup_fan_settings(priv); if (ret) return ret; --=20 2.53.0