[PATCH] hwmon: (occ) Lock mutex in shutdown to prevent race with occ_active

[PATCH] hwmon: (occ) Lock mutex in shutdown to prevent race with occ_active

[Eddie James]

Unbinding the driver or removing the parent device at the same time
as using the OCC active sysfs file can cause the driver to unregister
the hwmon device twice. Prevent this by locking the occ mutex in the
shutdown function.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
 drivers/hwmon/occ/common.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
index d78f4bebc718..ea070b91e5b9 100644
--- a/drivers/hwmon/occ/common.c
+++ b/drivers/hwmon/occ/common.c
@@ -1228,10 +1228,15 @@ EXPORT_SYMBOL_GPL(occ_setup);
 
 void occ_shutdown(struct occ *occ)
 {
+	mutex_lock(&occ->lock);
+
 	occ_shutdown_sysfs(occ);
 
 	if (occ->hwmon)
 		hwmon_device_unregister(occ->hwmon);
+	occ->hwmon = NULL;
+
+	mutex_unlock(&occ->lock);
 }
 EXPORT_SYMBOL_GPL(occ_shutdown);
 
-- 
2.31.1

Re: [PATCH] hwmon: (occ) Lock mutex in shutdown to prevent race with occ_active

[Guenter Roeck]

On Mon, Jun 06, 2022 at 01:54:55PM -0500, Eddie James wrote:
> Unbinding the driver or removing the parent device at the same time
> as using the OCC active sysfs file can cause the driver to unregister
> the hwmon device twice. Prevent this by locking the occ mutex in the
> shutdown function.
> 
> Signed-off-by: Eddie James <eajames@linux.ibm.com>

Applied.

Thanks,
Guenter

> ---
>  drivers/hwmon/occ/common.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
> index d78f4bebc718..ea070b91e5b9 100644
> --- a/drivers/hwmon/occ/common.c
> +++ b/drivers/hwmon/occ/common.c
> @@ -1228,10 +1228,15 @@ EXPORT_SYMBOL_GPL(occ_setup);
>  
>  void occ_shutdown(struct occ *occ)
>  {
> +	mutex_lock(&occ->lock);
> +
>  	occ_shutdown_sysfs(occ);
>  
>  	if (occ->hwmon)
>  		hwmon_device_unregister(occ->hwmon);
> +	occ->hwmon = NULL;
> +
> +	mutex_unlock(&occ->lock);
>  }
>  EXPORT_SYMBOL_GPL(occ_shutdown);
>