Re: [RFC PATCH] usb: host: xhci: allow __GFP_FS in dma allocation

Oliver Neukum
2019-05-22T06:31:47Z

On Di, 2019-05-21 at 10:00 -0400, Alan Stern wrote:
>
> Changing configurations amounts to much the same as disconnecting,
> because both operations destroy all the existing interfaces.
>
> Disconnect can arise in two different ways.
>
> Physical hot-unplug: All I/O operations will fail.
>
> Rmmod or unbind: I/O operations will succeed.
>
> The second case is probably okay. The first we can do nothing about.
> However, in either case we do need to make sure that memory allocations
> do not require any writebacks. This suggests that we need to call
> memalloc_noio_save() from within usb_unbind_interface().

I agree with the problem, but I fail to see why this issue would be
specific to USB. Shouldn't this be done in the device core layer?

Regards
Oliver