Re: [PATCH v2 1/1] usb: xhci: fix return value of xhci_setup_device()

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Sep 08, 2016 at 03:29:25PM +0800, Lu Baolu wrote:
> Hi Greg,
> 
> On 09/08/2016 02:38 PM, Greg KH wrote:
> > On Thu, Sep 08, 2016 at 08:41:02AM +0800, Lu Baolu wrote:
> >> xhci_setup_device() should return failure with correct error number
> >> when xhci host has died, removed or halted.
> >>
> >> Cc: stable@vger.kernel.org # 4.3+
> > Why is this a stable kernel issue?  What bug does it fix that affects
> > users?
> 
> During usb device enumeration, if xhci host is not accessible (died,
> removed or halted), the hc_driver->address_device() should return
> a corresponding error code to usb core. But current xhci driver just
> returns success. This will mislead usb core to continue enumeration:
> reading device descriptor, which will result in failure, and users will
> get a misleading message like "device descriptor read/8, error -110".

Why didn't you include this in the changelog text so that it is obvious
why this patch is needed?

Don't just describe what the patch does, we can read C code, describe
_why_ it is needed.

thanks,

greg k-h