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Sun, 05 Apr 2026 07:45:20 -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, edip@medip.dev, emreleno@gmail.com Subject: [PATCH v3 5/5] platform/x86: hp-wmi: add locking for concurrent hwmon access Date: Sun, 5 Apr 2026 17:45:00 +0300 Message-ID: <20260405144502.24944-6-emreleno@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260405144502.24944-1-emreleno@gmail.com> References: <20260405144502.24944-1-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() in a workqueue. A concurrent write and keep-alive expiry can observe an inconsistent mode/pwm pair (e.g. mode=3DMANUAL with a stale pwm). Add a mutex to hp_wmi_hwmon_priv protecting mode and pwm. Hold it in hp_wmi_hwmon_write() across the field update and apply call, and in hp_wmi_hwmon_keep_alive_handler() before calling apply. In hp_wmi_hwmon_read(), only the pwm_enable path reads priv->mode; use scoped_guard() there to avoid holding the lock across unrelated WMI calls. Fixes: c203c59fb5de ("platform/x86: hp-wmi: implement fan keep-alive") 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 db72ad9da0a5..1096fb46cbcd 100644 --- a/drivers/platform/x86/hp/hp-wmi.c +++ b/drivers/platform/x86/hp/hp-wmi.c @@ -453,6 +453,7 @@ enum pwm_modes { }; =20 struct hp_wmi_hwmon_priv { + struct mutex lock; /* protects mode, pwm */ u8 min_rpm; u8 max_rpm; int gpu_delta; @@ -2422,6 +2423,7 @@ 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) { @@ -2445,11 +2447,13 @@ 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 */ @@ -2467,6 +2471,7 @@ 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) { @@ -2535,6 +2540,8 @@ 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. @@ -2592,6 +2599,8 @@ 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