Re: [PATCH v2 1/3] firmware loader: Introduce new API - request_firmware_abort()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Nov 03, 2014 at 11:07:08AM +0800, Kweh Hock Leong wrote:
> From: "Kweh, Hock Leong" <hock.leong.kweh@intel.com>
> 
> Besides aborting through user helper interface, a new API
> request_firmware_abort() allows kernel driver module to abort the
> request_firmware() / request_firmware_nowait() when they are no
> longer needed. It is useful for cancelling an outstanding firmware
> load if initiated from inside a module where that module is in the
> process of being unloaded, since the unload function may not have
> a handle to the struct firmware_buf.
> 
> Note for people who use request_firmware_nowait():
> You are required to do your own synchronization after you call
> request_firmware_abort() in order to continue unloading the
> module. The example synchronization code shows below:
> 
> while (THIS_MODULE && module_refcount(THIS_MODULE))
> 	msleep(20);

As others have pointed out, this isn't ok, and is totally racy and
should never end up in a driver.  Never mess with THIS_MODULE from
within the same module, otherwise it's racy and broken code.

So can you please rework this to not require this?

thanks,

greg k-h