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

[Dan Williams]

Dionna Glaze wrote:
> If a kernel module registers a firmware upload API ops set, then it's
> unable to be moved due to effectively a cyclic reference that the module
> depends on the upload which depends on the module.
> 
> Instead, only require the try_module_get when an upload is requested to
> disallow unloading a module only while the upload is in progress.

Oh, interesting, I wondered why CXL did not uncover this loop in its
usage only to realize that CXL calls firmware registration from the
cxl_pci module, but the @module paramter passed to
firmware_upload_register() is the cxl_core module. I.e. we are
accidentally avoiding the problem. I assume other CONFIG_FW_UPLOAD users
simply do not test module removal.

However, I think the fix is simply to remove all module reference taking
by the firmware_loader core. It is the consumer's responsibility to call
firmware_upload_unregister() in its module removal path and that should
flush any and all future usage of the passed in ops structure.