Re: [PATCH v6 3/8] firmware_loader: Move module refcounts to allow unloading

[Tom Lendacky]

On 11/14/24 12:17, Dan Williams wrote:
> Russ Weight wrote:
> [..]
>> Clearly this would be an unexpected/unusual case. Someone with root
>> access would have to remove the device driver. I'm not sure how much
>> effort should be expended in preventing it - but this is the reasoning
>> behind the incrementing/decrementing of the module reference counts.
> 
> The module reference needs to be held only if the producer of those
> symbols can be removed without triggering some coordinated removal with
> action consumer. A driver that fails to call
> firmware_upload_unregister() in its module removal path is simply a driver
> with a memory-leak and use-after-free bug, not something the firmware
> upload core needs to worry about.
> 
> So, the prevention mechanism is "thou shalt use
> firmware_upload_unregister() correctly", and when that is in place
> explicit module references are not only redundant, but trying to
> implement them causes circular dependency loops.

I believe that is how other similar services, like debugfs, work, the
module is responsible for cleaning up.

Thanks,
Tom