August 26, 2021 8:01 PM, "Rob Herring" <robh@xxxxxxxxxx> wrote:
> On Wed, Aug 25, 2021 at 10:57 PM <yajun.deng@xxxxxxxxx> wrote:
>
>> August 25, 2021 9:55 PM, "Rob Herring" <robh@xxxxxxxxxx> wrote:
>>
>> On Wed, Aug 25, 2021 at 3:34 AM Yajun Deng <yajun.deng@xxxxxxxxx> wrote:
>>
>> device_del() should be called first and then called put_device() in
>> unregister path, becase if that the final reference count, the device
>> will be cleaned up via device_release() above. So use device_unregister()
>> instead.
>>
>> Fixes: 9885440b16b8 (PCI: Fix pci_host_bridge struct device release/free handling)
>> Signed-off-by: Yajun Deng <yajun.deng@xxxxxxxxx>
>> ---
>> drivers/pci/probe.c | 4 +---
>> 1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> NAK.
>>
>> The current code is correct. Go read the comments for device_add/device_del.
>>
>> But the device_unregister() is only contains device_del() and put_device(). It just put
>> device_del() before put_device().
>
> And that is the wrong order as we want to undo what the code above
> did. The put_device here is for the get_device we did. The put_device
> in device_unregister is for the get_device that device_register did
> (on success only).
>
> Logically, it is wrong too to call unregister if register failed. That
> would be like doing this:
>
> p = malloc(1);
> if (!p)
> free(p);
>
This is the raw code:
err = device_register(&bus->dev);
if (err)
goto unregister;
unregister:
put_device(&bridge->dev);
device_del(&bridge->dev);
This is my code:
err = device_register(&bus->dev);
if (err)
goto unregister;
unregister:
device_unregister(&bridge->dev);
The parameter in device_register() is bus->dev, but the parameter in device_unregister() is bridge->dev.The are different.
The bridge->dev is already success before called device_register().So it wouldn't be happen like your code.
> Rob
