On Thu, Jan 20, 2022 at 10:56:42AM -0700, Mathieu Poirier wrote:

Good morning,

On Mon, Jan 10, 2022 at 07:31:00AM +0000, Miaoqian Lin wrote:

...

device_register() calls device_initialize(), according to doc of device_initialize:

Use put_device() to give up your reference instead of freeing
* @dev directly once you have called this function.

That is _if_ device_initialize() is called manually. In this instance @dev is registered with device_register() and unregistered with device_unregister(). The latter conforms to the comment you pointed out and calls put_device() as expected.

I originally misunderstood the context - you are referring to the failure path in cscfg_create_device(). You are correct about needing to call put_device() but your solution will not work when the module is unloaded properly and device_unregister() is called by way of cscfg_clear_device(). In that case device_unregister() is already calling put_device().

Here simply calling put_device() instead of cscfg_dev_release() in the error path should do just fine. That will call cscfg_dev_release() and the memory allocated for cscfg_mgr will be release.

Thanks, Mathieu

...

To prevent potential memleak, use put_device() instead call kfree directly.

Signed-off-by: Miaoqian Lin linmq006@gmail.com

drivers/hwtracing/coresight/coresight-syscfg.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c index 43054568430f..007fa1c761a7 100644 --- a/drivers/hwtracing/coresight/coresight-syscfg.c +++ b/drivers/hwtracing/coresight/coresight-syscfg.c @@ -764,7 +764,7 @@ struct device *cscfg_device(void) /* Must have a release function or the kernel will complain on module unload */ static void cscfg_dev_release(struct device *dev) {

• kfree(cscfg_mgr);

• put_device(dev); cscfg_mgr = NULL;

} -- 2.17.1