linux-kernel - [PATCH] hwmon: (adt7470) Fix warning on module removal

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Message-Id: <20220407101312.13331-1-W_Armin@gmx.de>
Date:   Thu,  7 Apr 2022 12:13:12 +0200
From:   Armin Wolf <W_Armin@....de>
To:     zheyuma97@...il.com
Cc:     jdelvare@...e.com, linux@...ck-us.net, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] hwmon: (adt7470) Fix warning on module removal

When removing the adt7470 module, a warning might be printed:

do not call blocking ops when !TASK_RUNNING; state=1
set at [<ffffffffa006052b>] adt7470_update_thread+0x7b/0x130 [adt7470]

This happens because adt7470_update_thread() can leave the kthread in
TASK_INTERRUPTIBLE state when the kthread is being stopped before
the call of set_current_state(). Since kthread_exit() might sleep in
exit_signals(), the warning is printed.
Fix that by using schedule_timeout_interruptible() and removing
the call of set_current_state().
This causes TASK_INTERRUPTIBLE to be set after kthread_should_stop()
which might cause the kthread to exit.

Compile-tested only.

Reported-by: Zheyu Ma <zheyuma97@...il.com>
Fixes: 93cacfd41f82 (hwmon: (adt7470) Allow faster removal)
Signed-off-by: Armin Wolf <W_Armin@....de>
---
 drivers/hwmon/adt7470.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/adt7470.c b/drivers/hwmon/adt7470.c
index fb6d14d213a1..c67cd037a93f 100644
--- a/drivers/hwmon/adt7470.c
+++ b/drivers/hwmon/adt7470.c
@@ -19,6 +19,7 @@
 #include <linux/log2.h>
 #include <linux/kthread.h>
 #include <linux/regmap.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/util_macros.h>

@@ -294,11 +295,10 @@ static int adt7470_update_thread(void *p)
 		adt7470_read_temperatures(data);
 		mutex_unlock(&data->lock);

-		set_current_state(TASK_INTERRUPTIBLE);
 		if (kthread_should_stop())
 			break;

-		schedule_timeout(msecs_to_jiffies(data->auto_update_interval));
+		schedule_timeout_interruptible(msecs_to_jiffies(data->auto_update_interval));
 	}

 	return 0;
--
2.30.2