Re: [PATCH 00/22] Explicitly deny IRQ0 in the USB host drivers

[Sergey Shtylyov <s.shtylyov@omp.ru>]

On 10/19/21 10:31 AM, Greg Kroah-Hartman wrote:

[...]
>>> Here are 22 patches against the 'usb-next' branch of Greg KH's 'usb.git' repo.
>>> The affected drivers use platform_get_irq() which can return IRQ0 (considered
>>> invalid, according to Linus) that means broken HCD when passed to usb_add_hcd()
>>> called at the end of the probe methods. I think that the solution to this issue
>>> is either explicitly deny or accept IRQ0 in usb_add_hcd()... /but/ here's this
>>> patch set to get the things going...
>>
>> Why not fix the root of the problem for your platform that is failing to
>> assign a valid irq for the device?
>>
>> Are you going to make this change to all callers of this function in the
>> kernel tree?
> 
> Also, you should have gotten a huge WARNING in your kernel log if this
> happens to let you know that something bad is going on.

   That's the relatively recent addition, yet it doesn't override IRQ0 to s/th
like -EINVAL.

> Is this patch
> series going to really change any of that?

   How? It doesn't touch drivers/base/platform.c...

> 
> What is the root problem here that you are trying to paper over with
> this patchset?

   As I said, it would be preferrable to either deny IRQ0 in usb_add_hcd() or
just don't try to filter it out. The real problem is that usb_add_hcd() does
add a non-functioning HCD without the necessary IRQ handling (it only hooks
an IRQ when it's non-zero).

> thanks,
> 
> greg k-h

MBR, Sergey