The hwmon core registers the hwmon device before adding sensors to the thermal core. If that fails, the hwmon device is released and an error is returned to the caller. From the code flow, it appears to be necessary to free struct hwmon_device *, allocated with kzalloc(), in that situation. This is incorrect, since the data structure will be freed automatically in hwmon_dev_release() when device_unregister() is called. This used to result in a double free, which was found and fixed with commit 74e3512731bd ("hwmon: (core) Fix double-free in __hwmon_device_register()"). This is, however, not obvious; any reader may erroneously conclude that the data structure is not freed. Add comment explaining why kfree() is not necessary in this situation. Reported-by: Eduardo Valentin <eduval@xxxxxxxxxx> Cc: Eduardo Valentin <eduval@xxxxxxxxxx> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> --- drivers/hwmon/hwmon.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c index 429784edd5ff..d0f821bf8ab6 100644 --- a/drivers/hwmon/hwmon.c +++ b/drivers/hwmon/hwmon.c @@ -654,6 +654,12 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata, hwdev, j); if (err) { device_unregister(hdev); + /* + * Don't worry about hwdev; + * hwmon_dev_release(), called + * from device_unregister(), + * will free it. + */ goto ida_remove; } } -- 2.7.4