[PATCH 5.10.y] hwmon: (npcm750-pwm-fan): stop fan timer on device detach

[Sasha Levin <sashal@kernel.org>]

From: Hongyan Xu <getshell@seu.edu.cn>

[ Upstream commit f27f6976ea269219c1259a7c2f8c6dfe782540a3 ]

When a fan tach channel is present, npcm7xx_pwm_fan_probe() starts
fan_timer. The timer callback polls tach state and rearms the timer, but
the driver has no remove callback or devm cleanup action to stop it. On
device detach, the devm-managed driver data and I/O mappings can be
released while the timer is still pending or running.

Register a devm cleanup action before starting the timer and shut the
timer down synchronously from that action.

This issue was found by a static analysis tool.

Fixes: f1fd4a4db777 ("hwmon: Add NPCM7xx PWM and Fan driver")
Cc: stable@vger.kernel.org
Signed-off-by: Hongyan Xu <getshell@seu.edu.cn>
Link: https://lore.kernel.org/r/20260729100116.790-1-getshell@seu.edu.cn
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
[ changed `timer_shutdown_sync()` to `timer_delete_sync()` since the former is absent in 5.10 ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/npcm750-pwm-fan.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/hwmon/npcm750-pwm-fan.c b/drivers/hwmon/npcm750-pwm-fan.c
index 11a28609da3c7..dd34009c9400c 100644
--- a/drivers/hwmon/npcm750-pwm-fan.c
+++ b/drivers/hwmon/npcm750-pwm-fan.c
@@ -360,6 +360,11 @@ static void npcm7xx_fan_polling(struct timer_list *t)
 	add_timer(&data->fan_timer);
 }
 
+static void npcm7xx_fan_cleanup(void *timer)
+{
+	timer_delete_sync(timer);
+}
+
 static inline void npcm7xx_fan_compute(struct npcm7xx_pwm_fan_data *data,
 				       u8 fan, u8 cmp, u8 fan_id, u8 flag_int,
 				       u8 flag_mode, u8 flag_clear)
@@ -1003,6 +1008,12 @@ static int npcm7xx_pwm_fan_probe(struct platform_device *pdev)
 				msecs_to_jiffies(NPCM7XX_FAN_POLL_TIMER_200MS);
 			timer_setup(&data->fan_timer,
 				    npcm7xx_fan_polling, 0);
+			ret = devm_add_action_or_reset(dev,
+						       npcm7xx_fan_cleanup,
+						       &data->fan_timer);
+			if (ret)
+				return ret;
+
 			add_timer(&data->fan_timer);
 			break;
 		}
-- 
2.53.0