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Message-ID: <82718bec37e4e16e0a08b3b7a00452f99adc707b.camel@suse.de>
Subject: Re: [RFC] xhci: clear port_remote_wakeup on device disconnection
From:   Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To:     Oliver Neukum <oneukum@suse.com>,
        Mathias Nyman <mathias.nyman@intel.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
Date:   Tue, 19 Mar 2019 15:54:21 +0100
In-Reply-To: <1552993288.14757.23.camel@suse.com>
References: <20190318170038.23914-1-nsaenzjulienne@suse.de>
         <1552993288.14757.23.camel@suse.com>
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Hi Oliver, thanks for the review!

On Tue, 2019-03-19 at 12:01 +0100, Oliver Neukum wrote:
> On Mo, 2019-03-18 at 18:00 +0100, Nicolas Saenz Julienne wrote:
> > This patch clears "port_remote_wakeup" upon detecting a device
> > disconnection. Making sure the above mentioned situation doesn't trigge=
r
> > a PM busyloop.
>=20
> Hi,
>=20
> that is an interesting race condition.
>=20
> > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> > ---
> >  drivers/usb/host/xhci-hub.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >=20
> > diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
> > index e2eece693655..bea853f45aec 100644
> > --- a/drivers/usb/host/xhci-hub.c
> > +++ b/drivers/usb/host/xhci-hub.c
> > @@ -942,6 +942,9 @@ static void xhci_get_usb3_port_status(struct xhci_p=
ort
> > *port, u32 *status,
> >  			bus_state->suspended_ports &=3D ~(1 << portnum);
> >  	}
> > =20
> > +	if (!(portsc & PORT_CONNECT))
> > +		bus_state->port_remote_wakeup &=3D ~(1 << portnum);
> > +
> >  	xhci_hub_report_usb3_link_state(xhci, status, portsc);
> >  	xhci_del_comp_mod_timer(xhci, portsc, portnum);
> >  }
>=20
> Why are you putting that logic into xhci_get_usb3_port_status()?
> It looks to me like there is already something related in the caller
>=20
>         /* USB2 and USB3 specific bits, including Port Link State */
>         if (hcd->speed >=3D HCD_USB3)
>                 xhci_get_usb3_port_status(port, &status, raw_port_status)=
;
>         else
>                 xhci_get_usb2_port_status(port, &status, raw_port_status,
>                                           flags);
>         /*
>          * Clear stale usb2 resume signalling variables in case port chan=
ged
>          * state during resume signalling. For example on error
>          */
>         if ((bus_state->resume_done[wIndex] ||
>              test_bit(wIndex, &bus_state->resuming_ports)) &&
>             (raw_port_status & PORT_PLS_MASK) !=3D XDEV_U3 &&
>             (raw_port_status & PORT_PLS_MASK) !=3D XDEV_RESUME) {
>                 bus_state->resume_done[wIndex] =3D 0;
>                 clear_bit(wIndex, &bus_state->resuming_ports);
>                 usb_hcd_end_port_resume(&hcd->self, wIndex);
>         }

You're right, xhci_get_usb3_port_status() is not the ideal spot I'll move t=
he
code there.

>=20
> Otherwise very good catch!
>=20
> 	Regards
> 		Oliver
>=20


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