Re: [PATCH 1/2] usb: xhci: fix uninitialized completion when USB3 port got wrong status

[Mathias Nyman]

On 22.10.2018 20:53, Aaron Ma wrote:
> On 10/22/18 9:12 PM, Mathias Nyman wrote:
> > On 21.10.2018 20:08, Aaron Ma wrote:
> > > Realtek USB3.0 Card Reader [0bda:0328] reports wrong port status on
> > > Cannon lake PCH USB3.1 xHCI [8086:a36d] after resume from S3,
> > > after clear port reset it works fine.
> > >
> > > Since this device is registered on USB3 roothub at boot,
> > > when port status reports not superspeed, xhci_get_port_status will call
> > > an uninitialized completion in bus_state[0].
> > > Kernel will hang because of NULL pointer.
> > >
> > > Restrict the USB2 resume status check in USB2 roothub to fix hang issue.
> > > No harm to initialize USB3 bus_state[0] in case it is called.
> > >
> > > Signed-off-by: Aaron Ma <aaron.ma@xxxxxxxxxxxxx>
> > > ---
> > >   drivers/usb/host/xhci-hub.c | 2 +-
> > >   drivers/usb/host/xhci-mem.c | 1 >>>   drivers/usb/host/xhci-ring.c | 2 +-
> > >  Â 3 files changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
> > > index 7e2a531ba321..d30ca6ceffc9 100644
> > > --- a/drivers/usb/host/xhci-hub.c
> > > +++ b/drivers/usb/host/xhci-hub.c
> > > @@ -876,7 +876,7 @@ static u32 xhci_get_port_status(struct usb_hcd *hcd,
> > >  ÂÂÂÂÂÂÂÂÂÂÂÂÂ status |= USB_PORT_STAT_SUSPEND;
> > >  ÂÂÂÂÂ }
> > >  ÂÂÂÂÂ if ((raw_port_status & PORT_PLS_MASK) == XDEV_RESUME &&
> > > -ÂÂÂÂÂÂÂ !DEV_SUPERSPEED_ANY(raw_port_status)) {
> > > +ÂÂÂÂÂÂÂ !DEV_SUPERSPEED_ANY(raw_port_status) && 1 == hcd_index(hcd)) {
> > >  ÂÂÂÂÂÂÂÂÂ if ((raw_port_status & PORT_RESET) ||
> > >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ !(raw_port_status & PORT_PE))
> > >  ÂÂÂÂÂÂÂÂÂÂÂÂÂ return 0xffffffff;
> >
> > The original !DEV_SUPERSPEED_ANY() check was not suitable here.
> > It checks the port-speed field of portsc register (bits 13:10), which
> > are only valid for USB3
> > ports if all link training is done and port reached its "enabled" state.
> > Otherwise it will return 0, and USB3 ports may be mistaken for USB2 ports.
>
> PORT_ENABLE should be already set to one.
> The same device ID card reader doesn't have issue on Sunrise Point.
> Maybe it is related to Cannon lake PCH USB controller?

Ok, thanks for the info

> V2 sent out. Cc-ed stable.
>
> > Any chance you to check if the refactored code works with the Realtek
> > device?
> > I just created a "get_port_status_refactor" branch for it:
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git
> > get_port_status_refactor
>
> The hang issue is not reproduced on this kernel branch.

Great, thanks for testing it

-Mathias