Re: [PATCH] ata: disable port while unloading ATA controller driver

[Tejun Heo <tj@kernel.org>]

Hello, Vladimir.

On Tue, Nov 29, 2016 at 10:04:14PM +0200, Vladimir Zapolskiy wrote:
> > Not really.  Is this from the unloading test config?
> 
> Correct, I always get the warning with CONFIG_DEBUG_TEST_DRIVER_REMOVE
> option enabled.
> 
> I understand that a working solution might be just to disable the
> option rather than handle this case, however because it is wanted
> to test other drivers for potential errors also (e.g. the same ATA
> controller driver regardless of the false positive in the ATA core), 
> in my opinion the issue should not be ignored.

So, the problem is that CONFIG_DEBUG_TEST_DRIVER_REMOVE is introducing
a condition which isn't otherwise possible, so it's triggering pseudo
bugs.  The solution here is to make CONFIG_DEBUG_TEST_DRIVER_REMOVE
flush async calls before trying to remove the driver.

> > Control doesn't get passed to userland until async probings are
> > flushed, so this shouldn't normally be possible.
> > 
> 
> I'm not an expert in ATA, can you please show me the synchronization
> point?

async_synchronize_full() call in kernel_init() for booting and in
delete_module() for module unloading.

Thanks.

-- 
tejun